NAME
EVP_PKEY_decrypt_init,
EVP_PKEY_decrypt —
decrypt using a public key
algorithm
SYNOPSIS
#include
<openssl/evp.h>
int
EVP_PKEY_decrypt_init(EVP_PKEY_CTX
*ctx);
int
EVP_PKEY_decrypt(EVP_PKEY_CTX
*ctx, unsigned char *out, size_t
*outlen, const unsigned char *in,
size_t inlen);
DESCRIPTION
TheEVP_PKEY_decrypt_init()
function initializes a public key algorithm context using key
ctx->pkey for a decryption operation.
The
EVP_PKEY_decrypt()
function performs a public key decryption operation using
ctx. The data to be decrypted is specified using the
in and inlen parameters. If
out is NULL then the maximum
size of the output buffer is written to the outlen
parameter. If out is not NULL
then before the call the outlen parameter should
contain the length of the out buffer. If the call is
successful the decrypted data is written to out and
the amount of data written to outlen.
After the call to
EVP_PKEY_decrypt_init(),
algorithm specific control operations can be performed to set any
appropriate parameters for the operation.
The function
EVP_PKEY_decrypt()
can be called more than once on the same context if several operations are
performed using the same parameters.
RETURN VALUES
EVP_PKEY_decrypt_init() and
EVP_PKEY_decrypt() return 1 for success and 0 or a
negative value for failure. In particular, a return value of -2 indicates
the operation is not supported by the public key algorithm.
EXAMPLES
Decrypt data using OAEP (for RSA keys):
#include <openssl/evp.h> #include <openssl/rsa.h> EVP_PKEY_CTX *ctx; ENGINE *eng; unsigned char *out, *in; size_t outlen, inlen; EVP_PKEY *key; /* * Assumes that key, eng, in, and inlen are already set up * and that key is an RSA private key. */ ctx = EVP_PKEY_CTX_new(key, eng); if (!ctx) /* Error occurred */ if (EVP_PKEY_decrypt_init(ctx) <= 0) /* Error */ if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_OAEP_PADDING) <= 0) /* Error */ /* Determine buffer length */ if (EVP_PKEY_decrypt(ctx, NULL, &outlen, in, inlen) <= 0) /* Error */ out = malloc(outlen); if (!out) /* malloc failure */ if (EVP_PKEY_decrypt(ctx, out, &outlen, in, inlen) <= 0) /* Error */ /* Decrypted data is outlen bytes written to buffer out */
SEE ALSO
EVP_PKEY_CTX_new(3), EVP_PKEY_derive(3), EVP_PKEY_encrypt(3), EVP_PKEY_meth_set_decrypt(3), EVP_PKEY_sign(3), EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3)
HISTORY
EVP_PKEY_decrypt_init() and
EVP_PKEY_decrypt() first appeared in OpenSSL 1.0.0
and have been available since OpenBSD 4.9.