mirror of
https://github.com/openssl/openssl.git
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d84f5515fa
We don't want to hold a read lock when calling a user supplied callback. That callback could do anything so the risk of a deadlock is high. Instead we collect all the names first inside the read lock, and then subsequently call the user callback outside the read lock. Fixes #14225 Reviewed-by: Tomas Mraz <tomas@openssl.org> Reviewed-by: Paul Dale <pauli@openssl.org> (Merged from https://github.com/openssl/openssl/pull/14250)
382 lines
14 KiB
Plaintext
382 lines
14 KiB
Plaintext
=pod
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=head1 NAME
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EVP_RAND, EVP_RAND_fetch, EVP_RAND_free, EVP_RAND_up_ref, EVP_RAND_CTX,
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EVP_RAND_CTX_new, EVP_RAND_CTX_free, EVP_RAND_instantiate,
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EVP_RAND_uninstantiate, EVP_RAND_generate, EVP_RAND_reseed,
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EVP_RAND_nonce, EVP_RAND_enable_locking,
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EVP_RAND_verify_zeroization, EVP_RAND_strength, EVP_RAND_state,
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EVP_RAND_provider, EVP_RAND_CTX_rand, EVP_RAND_is_a, EVP_RAND_number,
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EVP_RAND_name, EVP_RAND_names_do_all, EVP_RAND_get_ctx_params,
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EVP_RAND_set_ctx_params, EVP_RAND_do_all_provided, EVP_RAND_get_params,
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EVP_RAND_gettable_ctx_params, EVP_RAND_settable_ctx_params,
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EVP_RAND_gettable_params, EVP_RAND_STATE_UNINITIALISED, EVP_RAND_STATE_READY,
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EVP_RAND_STATE_ERROR - EVP RAND routines
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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typedef struct evp_rand_st EVP_RAND;
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typedef struct evp_rand_ctx_st EVP_RAND_CTX;
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EVP_RAND *EVP_RAND_fetch(OSSL_LIB_CTX *libctx, const char *algorithm,
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const char *properties);
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int EVP_RAND_up_ref(EVP_RAND *rand);
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void EVP_RAND_free(EVP_RAND *rand);
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EVP_RAND_CTX *EVP_RAND_CTX_new(EVP_RAND *rand, EVP_RAND_CTX *parent);
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void EVP_RAND_CTX_free(EVP_RAND_CTX *ctx);
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EVP_RAND *EVP_RAND_CTX_rand(EVP_RAND_CTX *ctx);
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int EVP_RAND_get_params(EVP_RAND *rand, OSSL_PARAM params[]);
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int EVP_RAND_get_ctx_params(EVP_RAND_CTX *ctx, OSSL_PARAM params[]);
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int EVP_RAND_set_ctx_params(EVP_RAND_CTX *ctx, const OSSL_PARAM params[]);
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const OSSL_PARAM *EVP_RAND_gettable_params(const EVP_RAND *rand);
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const OSSL_PARAM *EVP_RAND_gettable_ctx_params(const EVP_RAND *rand);
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const OSSL_PARAM *EVP_RAND_settable_ctx_params(const EVP_RAND *rand);
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int EVP_RAND_number(const EVP_RAND *rand);
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const char *EVP_RAND_name(const EVP_RAND *rand);
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int EVP_RAND_is_a(const EVP_RAND *rand, const char *name);
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const OSSL_PROVIDER *EVP_RAND_provider(const EVP_RAND *rand);
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void EVP_RAND_do_all_provided(OSSL_LIB_CTX *libctx,
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void (*fn)(EVP_RAND *rand, void *arg),
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void *arg);
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int EVP_RAND_names_do_all(const EVP_RAND *rand,
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void (*fn)(const char *name, void *data),
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void *data);
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int EVP_RAND_instantiate(EVP_RAND_CTX *ctx, unsigned int strength,
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int prediction_resistance,
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const unsigned char *pstr, size_t pstr_len);
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int EVP_RAND_uninstantiate(EVP_RAND_CTX *ctx);
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int EVP_RAND_generate(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen,
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unsigned int strength, int prediction_resistance,
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const unsigned char *addin, size_t addin_len);
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int EVP_RAND_reseed(EVP_RAND_CTX *ctx, int prediction_resistance,
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const unsigned char *ent, size_t ent_len,
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const unsigned char *addin, size_t addin_len);
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int EVP_RAND_nonce(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen);
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int EVP_RAND_enable_locking(EVP_RAND_CTX *ctx);
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int EVP_RAND_verify_zeroization(EVP_RAND_CTX *ctx);
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unsigned int EVP_RAND_strength(EVP_RAND_CTX *ctx);
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int EVP_RAND_state(EVP_RAND_CTX *ctx);
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#define EVP_RAND_STATE_UNINITIALISED 0
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#define EVP_RAND_STATE_READY 1
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#define EVP_RAND_STATE_ERROR 2
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=head1 DESCRIPTION
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The EVP RAND routines are a high-level interface to random number generators
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both deterministic and not.
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If you just want to generate random bytes then you don't need to use
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these functions: just call RAND_bytes() or RAND_priv_bytes().
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If you want to do more, these calls should be used instead of the older
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RAND and RAND_DRBG functions.
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After creating a B<EVP_RAND_CTX> for the required algorithm using
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EVP_RAND_CTX_new(), inputs to the algorithm are supplied
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using calls to EVP_RAND_set_ctx_params() before
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calling EVP_RAND_instantiate() and then EVP_RAND_generate() to produce
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cryptographically secure random bytes.
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=head2 Types
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B<EVP_RAND> is a type that holds the implementation of a RAND.
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B<EVP_RAND_CTX> is a context type that holds the algorithm inputs.
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B<EVP_RAND_CTX> structures are reference counted.
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=head2 Algorithm implementation fetching
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EVP_RAND_fetch() fetches an implementation of a RAND I<algorithm>, given
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a library context I<libctx> and a set of I<properties>.
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See L<provider(7)/Fetching algorithms> for further information.
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The returned value must eventually be freed with
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L<EVP_RAND_free(3)>.
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EVP_RAND_up_ref() increments the reference count of an already fetched
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RAND.
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EVP_RAND_free() frees a fetched algorithm.
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NULL is a valid parameter, for which this function is a no-op.
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=head2 Context manipulation functions
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EVP_RAND_CTX_new() creates a new context for the RAND implementation I<rand>.
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If not NULL, I<parent> specifies the seed source for this implementation.
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Not all random number generators need to have a seed source specified.
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If a parent is required, a NULL I<parent> will utilise the operating
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system entropy sources.
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It is recommended to minimise the number of random number generators that
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rely on the operating system for their randomness because this is often scarce.
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EVP_RAND_CTX_free() frees up the context I<ctx>. If I<ctx> is NULL, nothing
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is done.
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EVP_RAND_CTX_rand() returns the B<EVP_RAND> associated with the context
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I<ctx>.
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=head2 Random Number Generator Functions
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EVP_RAND_instantiate() instantiates the RAND I<ctx> with a minimum security
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strength of <strength> and personalisation string I<pstr> of length <pstr_len>.
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If I<prediction_resistance> is specified, fresh entropy from a live source
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will be sought. This call operates as per NIST SP 800-90A and SP 800-90C.
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EVP_RAND_uninstantiate() uninstantiates the RAND I<ctx> as per
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NIST SP 800-90A and SP 800-90C. Subsequent to this call, the RAND cannot
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be used to generate bytes. It can only be freed or instantiated again.
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EVP_RAND_generate() produces random bytes from the RAND I<ctx> with the
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additional input I<addin> of length I<addin_len>. The bytes
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produced will meet the security I<strength>.
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If I<prediction_resistance> is specified, fresh entropy from a live source
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will be sought. This call operates as per NIST SP 800-90A and SP 800-90C.
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EVP_RAND_reseed() reseeds the RAND with new entropy.
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Entropy I<ent> of length I<ent_len> bytes can be supplied as can additional
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input I<addin> of length I<addin_len> bytes. In the FIPS provider, both are
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treated as additional input as per NIST SP-800-90Ar1, Sections 9.1 and 9.2.
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Additional seed material is also drawn from the RAND's parent or the
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operating system. If I<prediction_resistance> is specified, fresh entropy
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from a live source will be sought. This call operates as per NIST SP 800-90A
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and SP 800-90C.
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EVP_RAND_nonce() creates a nonce in I<out> of maximum length I<outlen>
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bytes from the RAND I<ctx>. The function returns the length of the generated
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nonce. If I<out> is NULL, the length is still returned but no generation
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takes place. This allows a caller to dynamically allocate a buffer of the
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appropriate size.
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EVP_RAND_enable_locking() enables locking for the RAND I<ctx> and all of
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its parents. After this I<ctx> will operate in a thread safe manner, albeit
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more slowly. This function is not itself thread safe if called with the same
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I<ctx> from multiple threads. Typically locking should be enabled before a
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I<ctx> is shared across multiple threads.
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EVP_RAND_get_params() retrieves details about the implementation
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I<rand>.
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The set of parameters given with I<params> determine exactly what
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parameters should be retrieved.
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Note that a parameter that is unknown in the underlying context is
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simply ignored.
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EVP_RAND_get_ctx_params() retrieves chosen parameters, given the
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context I<ctx> and its underlying context.
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The set of parameters given with I<params> determine exactly what
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parameters should be retrieved.
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Note that a parameter that is unknown in the underlying context is
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simply ignored.
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EVP_RAND_set_ctx_params() passes chosen parameters to the underlying
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context, given a context I<ctx>.
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The set of parameters given with I<params> determine exactly what
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parameters are passed down.
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Note that a parameter that is unknown in the underlying context is
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simply ignored.
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Also, what happens when a needed parameter isn't passed down is
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defined by the implementation.
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EVP_RAND_gettable_params(), EVP_RAND_gettable_ctx_params() and
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EVP_RAND_settable_ctx_params() get a constant B<OSSL_PARAM> array that
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describes the retrievable and settable parameters, i.e. parameters that
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can be used with EVP_RAND_get_params(), EVP_RAND_get_ctx_params()
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and EVP_RAND_set_ctx_params(), respectively.
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See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
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=head2 Information functions
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EVP_RAND_strength() returns the security strength of the RAND I<ctx>.
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EVP_RAND_state() returns the current state of the RAND I<ctx>.
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States defined by the OpenSSL RNGs are:
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=over 4
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=item *
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EVP_RAND_STATE_UNINITIALISED: this RNG is currently uninitialised.
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The instantiate call will change this to the ready state.
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=item *
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EVP_RAND_STATE_READY: this RNG is currently ready to generate output.
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=item *
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EVP_RAND_STATE_ERROR: this RNG is in an error state.
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=back
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EVP_RAND_is_a() returns 1 if I<rand> is an implementation of an
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algorithm that's identifiable with I<name>, otherwise 0.
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EVP_RAND_provider() returns the provider that holds the implementation
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of the given I<rand>.
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EVP_RAND_do_all_provided() traverses all RAND implemented by all activated
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providers in the given library context I<libctx>, and for each of the
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implementations, calls the given function I<fn> with the implementation method
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and the given I<arg> as argument.
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EVP_RAND_number() returns the internal dynamic number assigned to
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I<rand>.
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EVP_RAND_name() returns the canonical name of I<rand>.
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EVP_RAND_names_do_all() traverses all names for I<rand>, and calls
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I<fn> with each name and I<data>.
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EVP_RAND_verify_zeroization() confirms if the internal DRBG state is
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currently zeroed. This is used by the FIPS provider to support the mandatory
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self tests.
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=head1 PARAMETERS
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The standard parameter names are:
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=over 4
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=item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
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Returns the state of the random number generator.
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=item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
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Returns the bit strength of the random number generator.
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=back
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For rands that are also deterministic random bit generators (DRBGs), these
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additional parameters are recognised. Not all
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parameters are relevant to, or are understood by all DRBG rands:
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=over 4
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=item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
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Reads or set the number of generate requests before reseeding the
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associated RAND ctx.
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=item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
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Reads or set the number of elapsed seconds before reseeding the
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associated RAND ctx.
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=item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
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Specifies the maximum number of bytes that can be generated in a single
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call to OSSL_FUNC_rand_generate.
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=item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
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=item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
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Specify the minimum and maximum number of bytes of random material that
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can be used to seed the DRBG.
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=item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
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=item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
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Specify the minimum and maximum number of bytes of nonce that can be used to
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seed the DRBG.
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=item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
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=item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
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Specify the minimum and maximum number of bytes of personalisation string
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that can be used with the DRBG.
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=item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer>
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Specifies the number of times the DRBG has been seeded or reseeded.
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=item "properties" (B<OSSL_RAND_PARAM_PROPERTIES>) <UTF8 string>
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=item "mac" (B<OSSL_RAND_PARAM_MAC>) <UTF8 string>
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=item "digest" (B<OSSL_RAND_PARAM_DIGEST>) <UTF8 string>
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=item "cipher" (B<OSSL_RAND_PARAM_CIPHER>) <UTF8 string>
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For RAND implementations that use an underlying computation MAC, digest or
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cipher, these parameters set what the algorithm should be.
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The value is always the name of the intended algorithm,
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or the properties in the case of B<OSSL_RAND_PARAM_PROPERTIES>.
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=back
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=head1 NOTES
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An B<EVP_RAND_CTX> needs to have locking enabled if it acts as the parent of
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more than one child and the children can be accessed concurrently. This must
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be done by explicitly calling EVP_RAND_enable_locking().
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=head1 RETURN VALUES
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EVP_RAND_fetch() returns a pointer to a newly fetched B<EVP_RAND>, or
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NULL if allocation failed.
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EVP_RAND_provider() returns a pointer to the provider for the RAND, or
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NULL on error.
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EVP_RAND_CTX_rand() returns a pointer to the B<EVP_RAND> associated with the
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context.
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EVP_RAND_name() returns the name of the random number generation algorithm.
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EVP_RAND_number() returns the provider specific identification number
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for the specified algorithm.
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EVP_RAND_up_ref() returns 1 on success, 0 on error.
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EVP_RAND_names_do_all() returns 1 if the callback was called for all names. A
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return value of 0 means that the callback was not called for any names.
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EVP_RAND_CTX_new() returns either the newly allocated
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B<EVP_RAND_CTX> structure or NULL if an error occurred.
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EVP_RAND_CTX_free() does not return a value.
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EVP_RAND_nonce() returns the length of the nonce.
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EVP_RAND_strength() returns the strength of the random number generator in bits.
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EVP_RAND_gettable_params(), EVP_RAND_gettable_ctx_params() and
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EVP_RAND_settable_ctx_params() return an array of OSSL_PARAMs.
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EVP_RAND_verify_zeroization() returns 1 if the internal DRBG state is
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currently zeroed, and 0 if not.
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The remaining functions return 1 for success and 0 or a negative value for
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failure.
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=head1 SEE ALSO
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L<RAND_bytes(3)>,
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L<EVP_RAND-CTR-DRBG(7)>,
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L<EVP_RAND-HASH-DRBG(7)>,
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L<EVP_RAND-HMAC-DRBG(7)>,
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L<EVP_RAND-TEST-RAND(7)>,
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L<provider-rand(7)>
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=head1 HISTORY
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This functionality was added to OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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