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| 1 =pod |
| 2 |
| 3 =head1 NAME |
| 4 |
| 5 EVP_PKEY_sign_init, EVP_PKEY_sign - sign using a public key algorithm |
| 6 |
| 7 =head1 SYNOPSIS |
| 8 |
| 9 #include <openssl/evp.h> |
| 10 |
| 11 int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx); |
| 12 int EVP_PKEY_sign(EVP_PKEY_CTX *ctx, |
| 13 unsigned char *sig, size_t *siglen, |
| 14 const unsigned char *tbs, size_t tbslen); |
| 15 |
| 16 =head1 DESCRIPTION |
| 17 |
| 18 The EVP_PKEY_sign_init() function initializes a public key algorithm |
| 19 context using key B<pkey> for a signing operation. |
| 20 |
| 21 The EVP_PKEY_sign() function performs a public key signing operation |
| 22 using B<ctx>. The data to be signed is specified using the B<tbs> and |
| 23 B<tbslen> parameters. If B<sig> is B<NULL> then the maximum size of the output |
| 24 buffer is written to the B<siglen> parameter. If B<sig> is not B<NULL> then |
| 25 before the call the B<siglen> parameter should contain the length of the |
| 26 B<sig> buffer, if the call is successful the signature is written to |
| 27 B<sig> and the amount of data written to B<siglen>. |
| 28 |
| 29 =head1 NOTES |
| 30 |
| 31 After the call to EVP_PKEY_sign_init() algorithm specific control |
| 32 operations can be performed to set any appropriate parameters for the |
| 33 operation. |
| 34 |
| 35 The function EVP_PKEY_sign() can be called more than once on the same |
| 36 context if several operations are performed using the same parameters. |
| 37 |
| 38 =head1 RETURN VALUES |
| 39 |
| 40 EVP_PKEY_sign_init() and EVP_PKEY_sign() return 1 for success and 0 |
| 41 or a negative value for failure. In particular a return value of -2 |
| 42 indicates the operation is not supported by the public key algorithm. |
| 43 |
| 44 =head1 EXAMPLE |
| 45 |
| 46 Sign data using RSA with PKCS#1 padding and SHA256 digest: |
| 47 |
| 48 #include <openssl/evp.h> |
| 49 #include <openssl/rsa.h> |
| 50 |
| 51 EVP_PKEY_CTX *ctx; |
| 52 unsigned char *md, *sig; |
| 53 size_t mdlen, siglen; |
| 54 EVP_PKEY *signing_key; |
| 55 /* NB: assumes signing_key, md and mdlen are already set up |
| 56 * and that signing_key is an RSA private key |
| 57 */ |
| 58 ctx = EVP_PKEY_CTX_new(signing_key); |
| 59 if (!ctx) |
| 60 /* Error occurred */ |
| 61 if (EVP_PKEY_sign_init(ctx) <= 0) |
| 62 /* Error */ |
| 63 if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0) |
| 64 /* Error */ |
| 65 if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) |
| 66 /* Error */ |
| 67 |
| 68 /* Determine buffer length */ |
| 69 if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0) |
| 70 /* Error */ |
| 71 |
| 72 sig = OPENSSL_malloc(siglen); |
| 73 |
| 74 if (!sig) |
| 75 /* malloc failure */ |
| 76 |
| 77 if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0) |
| 78 /* Error */ |
| 79 |
| 80 /* Signature is siglen bytes written to buffer sig */ |
| 81 |
| 82 |
| 83 =head1 SEE ALSO |
| 84 |
| 85 L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>, |
| 86 L<EVP_PKEY_encrypt(3)|EVP_PKEY_encrypt(3)>, |
| 87 L<EVP_PKEY_decrypt(3)|EVP_PKEY_decrypt(3)>, |
| 88 L<EVP_PKEY_verify(3)|EVP_PKEY_verify(3)>, |
| 89 L<EVP_PKEY_verifyrecover(3)|EVP_PKEY_verifyrecover(3)>, |
| 90 L<EVP_PKEY_derive(3)|EVP_PKEY_derive(3)> |
| 91 |
| 92 =head1 HISTORY |
| 93 |
| 94 These functions were first added to OpenSSL 1.0.0. |
| 95 |
| 96 =cut |
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