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221 lines
9.9 KiB
Plaintext
221 lines
9.9 KiB
Plaintext
=pod
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=head1 NAME
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EVP_PKEY,
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EVP_PKEY_new,
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EVP_PKEY_up_ref,
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EVP_PKEY_dup,
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EVP_PKEY_free,
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EVP_PKEY_new_raw_private_key_ex,
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EVP_PKEY_new_raw_private_key,
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EVP_PKEY_new_raw_public_key_ex,
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EVP_PKEY_new_raw_public_key,
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EVP_PKEY_new_CMAC_key,
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EVP_PKEY_new_mac_key,
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EVP_PKEY_get_raw_private_key,
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EVP_PKEY_get_raw_public_key
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- public/private key allocation and raw key handling functions
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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typedef evp_pkey_st EVP_PKEY;
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EVP_PKEY *EVP_PKEY_new(void);
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int EVP_PKEY_up_ref(EVP_PKEY *key);
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EVP_PKEY *EVP_PKEY_dup(EVP_PKEY *key);
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void EVP_PKEY_free(EVP_PKEY *key);
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EVP_PKEY *EVP_PKEY_new_raw_private_key_ex(OSSL_LIB_CTX *libctx,
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const char *keytype,
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const char *propq,
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const unsigned char *key,
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size_t keylen);
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EVP_PKEY *EVP_PKEY_new_raw_private_key(int type, ENGINE *e,
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const unsigned char *key, size_t keylen);
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EVP_PKEY *EVP_PKEY_new_raw_public_key_ex(OSSL_LIB_CTX *libctx,
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const char *keytype,
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const char *propq,
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const unsigned char *key,
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size_t keylen);
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EVP_PKEY *EVP_PKEY_new_raw_public_key(int type, ENGINE *e,
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const unsigned char *key, size_t keylen);
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EVP_PKEY *EVP_PKEY_new_mac_key(int type, ENGINE *e, const unsigned char *key,
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int keylen);
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int EVP_PKEY_get_raw_private_key(const EVP_PKEY *pkey, unsigned char *priv,
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size_t *len);
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int EVP_PKEY_get_raw_public_key(const EVP_PKEY *pkey, unsigned char *pub,
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size_t *len);
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The following function has been deprecated since OpenSSL 3.0, and can be
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hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
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see L<openssl_user_macros(7)>:
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EVP_PKEY *EVP_PKEY_new_CMAC_key(ENGINE *e, const unsigned char *priv,
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size_t len, const EVP_CIPHER *cipher);
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=head1 DESCRIPTION
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B<EVP_PKEY> is a generic structure to hold diverse types of asymmetric keys
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(also known as "key pairs"), and can be used for diverse operations, like
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signing, verifying signatures, key derivation, etc. The asymmetric keys
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themselves are often referred to as the "internal key", and are handled by
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backends, such as providers (through L<EVP_KEYMGMT(3)>) or B<ENGINE>s.
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Conceptually, an B<EVP_PKEY> internal key may hold a private key, a public
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key, or both (a keypair), and along with those, key parameters if the key type
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requires them. The presence of these components determine what operations can
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be made; for example, signing normally requires the presence of a private key,
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and verifying normally requires the presence of a public key.
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=for comment ED signature require both the private and public key...
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B<EVP_PKEY> has also been used for MAC algorithm that were conceived as
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producing signatures, although not being public key algorithms; "POLY1305",
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"SIPHASH", "HMAC", "CMAC". This usage is considered legacy and is discouraged
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in favor of the L<EVP_MAC(3)> API.
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The EVP_PKEY_new() function allocates an empty B<EVP_PKEY> structure which is
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used by OpenSSL to store public and private keys. The reference count is set to
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B<1>.
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EVP_PKEY_up_ref() increments the reference count of I<key>.
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EVP_PKEY_dup() duplicates the I<key>. The I<key> must not be ENGINE based or
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a raw key, otherwise the duplication will fail.
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EVP_PKEY_free() decrements the reference count of I<key> and, if the reference
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count is zero, frees it up. If I<key> is NULL, nothing is done.
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EVP_PKEY_new_raw_private_key_ex() allocates a new B<EVP_PKEY>. Unless an
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engine should be used for the key type, a provider for the key is found using
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the library context I<libctx> and the property query string I<propq>. The
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I<keytype> argument indicates what kind of key this is. The value should be a
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string for a public key algorithm that supports raw private keys, i.e one of
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"X25519", "ED25519", "X448" or "ED448". I<key> points to the raw private key
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data for this B<EVP_PKEY> which should be of length I<keylen>. The length
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should be appropriate for the type of the key. The public key data will be
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automatically derived from the given private key data (if appropriate for the
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algorithm type).
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EVP_PKEY_new_raw_private_key() does the same as
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EVP_PKEY_new_raw_private_key_ex() except that the default library context and
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default property query are used instead. If I<e> is non-NULL then the new
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B<EVP_PKEY> structure is associated with the engine I<e>. The I<type> argument
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indicates what kind of key this is. The value should be a NID for a public key
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algorithm that supports raw private keys, i.e. one of B<EVP_PKEY_X25519>,
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B<EVP_PKEY_ED25519>, B<EVP_PKEY_X448> or B<EVP_PKEY_ED448>.
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EVP_PKEY_new_raw_private_key_ex() and EVP_PKEY_new_raw_private_key() may also
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be used with most MACs implemented as public key algorithms, so key types such
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as "HMAC", "POLY1305", "SIPHASH", or their NID form B<EVP_PKEY_POLY1305>,
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B<EVP_PKEY_SIPHASH>, B<EVP_PKEY_HMAC> are also accepted. This usage is,
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as mentioned above, discouraged in favor of the L<EVP_MAC(3)> API.
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EVP_PKEY_new_raw_public_key_ex() works in the same way as
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EVP_PKEY_new_raw_private_key_ex() except that I<key> points to the raw
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public key data. The B<EVP_PKEY> structure will be initialised without any
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private key information. Algorithm types that support raw public keys are
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"X25519", "ED25519", "X448" or "ED448".
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EVP_PKEY_new_raw_public_key() works in the same way as
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EVP_PKEY_new_raw_private_key() except that I<key> points to the raw public key
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data. The B<EVP_PKEY> structure will be initialised without any private key
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information. Algorithm types that support raw public keys are
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B<EVP_PKEY_X25519>, B<EVP_PKEY_ED25519>, B<EVP_PKEY_X448> or B<EVP_PKEY_ED448>.
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EVP_PKEY_new_mac_key() works in the same way as EVP_PKEY_new_raw_private_key().
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New applications should use EVP_PKEY_new_raw_private_key() instead.
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EVP_PKEY_get_raw_private_key() fills the buffer provided by I<priv> with raw
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private key data. The size of the I<priv> buffer should be in I<*len> on entry
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to the function, and on exit I<*len> is updated with the number of bytes
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actually written. If the buffer I<priv> is NULL then I<*len> is populated with
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the number of bytes required to hold the key. The calling application is
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responsible for ensuring that the buffer is large enough to receive the private
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key data. This function only works for algorithms that support raw private keys.
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Currently this is: B<EVP_PKEY_HMAC>, B<EVP_PKEY_POLY1305>, B<EVP_PKEY_SIPHASH>,
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B<EVP_PKEY_X25519>, B<EVP_PKEY_ED25519>, B<EVP_PKEY_X448> or B<EVP_PKEY_ED448>.
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EVP_PKEY_get_raw_public_key() fills the buffer provided by I<pub> with raw
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public key data. The size of the I<pub> buffer should be in I<*len> on entry
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to the function, and on exit I<*len> is updated with the number of bytes
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actually written. If the buffer I<pub> is NULL then I<*len> is populated with
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the number of bytes required to hold the key. The calling application is
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responsible for ensuring that the buffer is large enough to receive the public
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key data. This function only works for algorithms that support raw public keys.
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Currently this is: B<EVP_PKEY_X25519>, B<EVP_PKEY_ED25519>, B<EVP_PKEY_X448> or
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B<EVP_PKEY_ED448>.
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EVP_PKEY_new_CMAC_key() works in the same way as EVP_PKEY_new_raw_private_key()
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except it is only for the B<EVP_PKEY_CMAC> algorithm type. In addition to the
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raw private key data, it also takes a cipher algorithm to be used during
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creation of a CMAC in the B<cipher> argument. The cipher should be a standard
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encryption-only cipher. For example AEAD and XTS ciphers should not be used.
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Applications should use the L<EVP_MAC(3)> API instead
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and set the B<OSSL_MAC_PARAM_CIPHER> parameter on the B<EVP_MAC_CTX> object
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with the name of the cipher being used.
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=head1 NOTES
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The B<EVP_PKEY> structure is used by various OpenSSL functions which require a
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general private key without reference to any particular algorithm.
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The structure returned by EVP_PKEY_new() is empty. To add a private or public
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key to this empty structure use the appropriate functions described in
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L<EVP_PKEY_set1_RSA(3)>, L<EVP_PKEY_set1_DSA(3)>, L<EVP_PKEY_set1_DH(3)> or
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L<EVP_PKEY_set1_EC_KEY(3)>.
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=head1 RETURN VALUES
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EVP_PKEY_new(), EVP_PKEY_new_raw_private_key(), EVP_PKEY_new_raw_public_key(),
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EVP_PKEY_new_CMAC_key() and EVP_PKEY_new_mac_key() return either the newly
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allocated B<EVP_PKEY> structure or NULL if an error occurred.
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EVP_PKEY_dup() returns the key duplicate or NULL if an error occurred.
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EVP_PKEY_up_ref(), EVP_PKEY_get_raw_private_key() and
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EVP_PKEY_get_raw_public_key() return 1 for success and 0 for failure.
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=head1 SEE ALSO
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L<EVP_PKEY_set1_RSA(3)>, L<EVP_PKEY_set1_DSA(3)>, L<EVP_PKEY_set1_DH(3)> or
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L<EVP_PKEY_set1_EC_KEY(3)>
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=head1 HISTORY
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The
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EVP_PKEY_new() and EVP_PKEY_free() functions exist in all versions of OpenSSL.
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The EVP_PKEY_up_ref() function was added in OpenSSL 1.1.0.
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The
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EVP_PKEY_new_raw_private_key(), EVP_PKEY_new_raw_public_key(),
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EVP_PKEY_new_CMAC_key(), EVP_PKEY_new_raw_private_key() and
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EVP_PKEY_get_raw_public_key() functions were added in OpenSSL 1.1.1.
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The EVP_PKEY_dup(), EVP_PKEY_new_raw_private_key_ex(), and
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EVP_PKEY_new_raw_public_key_ex()
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functions were added in OpenSSL 3.0.
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The EVP_PKEY_new_CMAC_key() was deprecated in OpenSSL 3.0.
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The documentation of B<EVP_PKEY> was amended in OpenSSL 3.0 to allow there to
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be the private part of the keypair without the public part, where this was
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previously implied to be disallowed.
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=head1 COPYRIGHT
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Copyright 2002-2022 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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