X509_SIGN(3)

NAME
X509_sign, X509_sign_ctx, X509_verify, X509_REQ_sign, X509_REQ_sign_ctx, X509_REQ_verify, X509_CRL_sign, X509_CRL_sign_ctx, X509_CRL_verify - sign or verify certificate, certificate request, or CRL signature

SYNOPSIS
#include <openssl/x509.h>
int
X509_sign(X509 *x, EVP_PKEY *pkey, const EVP_MD *md);
int
X509_sign_ctx(X509 *x, EVP_MD_CTX *ctx);
int
X509_verify(X509 *a, EVP_PKEY *r);
int
X509_REQ_sign(X509_REQ *x, EVP_PKEY *pkey, const EVP_MD *md);
int
X509_REQ_sign_ctx(X509_REQ *x, EVP_MD_CTX *ctx);
int
X509_REQ_verify(X509_REQ *a, EVP_PKEY *r);
int
X509_CRL_sign(X509_CRL *x, EVP_PKEY *pkey, const EVP_MD *md);
int
X509_CRL_sign_ctx(X509_CRL *x, EVP_MD_CTX *ctx);
int
X509_CRL_verify(X509_CRL *a, EVP_PKEY *r);

DESCRIPTION
X509_sign() signs the certificate x using the private key pkey and the message digest md and sets the signature in x. X509_sign_ctx() also signs the certificate x but uses the parameters contained in digest context ctx.

X509_verify() verifies the signature of certificate x using the public key pkey. Only the signature is checked: no other checks (such as certificate chain validity) are performed.

X509_REQ_sign(), X509_REQ_sign_ctx(), X509_REQ_verify(), X509_CRL_sign(), X509_CRL_sign_ctx(), and X509_CRL_verify() sign and verify certificate requests and CRLs, respectively.

X509_sign_ctx() is used where the default parameters for the corresponding public key and digest are not suitable. It can be used to sign keys using RSA-PSS for example.

For efficiency reasons and to work around ASN.1 encoding issues, the encoding of the signed portion of a certificate, certificate request, and CRL is cached internally. If the signed portion of the structure is modified, the encoding is not always updated, meaning a stale version is sometimes used. This is not normally a problem because modifying the signed portion will invalidate the signature and signing will always update the encoding.

RETURN VALUES
X509_sign(), X509_sign_ctx(), X509_REQ_sign(), X509_REQ_sign_ctx(), X509_CRL_sign(), and X509_CRL_sign_ctx() return the size of the signature in bytes for success or 0 for failure.

X509_verify(), X509_REQ_verify(), and X509_CRL_verify() return 1 if the signature is valid or 0 if the signature check fails. If the signature could not be checked at all because it was invalid or some other error occurred, then -1 is returned.

In some cases of failure, the reason can be determined with ERR_get_error(3).

SEE ALSO
d2i_X509(3), EVP_DigestInit(3), X509_CRL_get0_by_serial(3), X509_CRL_new(3), X509_get_pubkey(3), X509_get_subject_name(3), X509_get_version(3), X509_NAME_add_entry_by_txt(3), X509_NAME_ENTRY_get_object(3), X509_NAME_get_index_by_NID(3), X509_NAME_print_ex(3), X509_new(3), X509_REQ_new(3), X509_verify_cert(3), X509V3_get_d2i(3)

HISTORY
X509_verify() appeared in SSLeay 0.4 or earlier. X509_sign() and X509_REQ_sign() first appeared in SSLeay 0.4.4. X509_REQ_verify() and X509_CRL_verify() first appeared in SSLeay 0.4.5b. X509_CRL_sign() first appeared in SSLeay 0.5.1. These functions have been available since OpenBSD 2.4.

X509_sign_ctx(), X509_REQ_sign_ctx(), and X509_CRL_sign_ctx() first appeared in OpenSSL 1.0.1 and have been available since OpenBSD 5.3.