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EVP_PKEY_DECRYPT(3) | Library Functions Manual | EVP_PKEY_DECRYPT(3) |
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.March 31, 2022 | Debian |