是的 - 这很麻烦。下面是我正在使用的代码。它使用SecKeyGeneratePair()生成的密钥进行签名(因此在keychain/外部可达)。
对我来说，破解这个问题的关键是发现SecKeyRawSign只支持SHA1。
如果您想接手一些现有的运行代码，清理它，添加文档，然后以一个漂亮的Apache许可证放在github上供所有人使用，请随时私信联系我。
(NSData *)signCSR:(NSData *)derCSR forDays:(double)days NIDstToKeep:(NSSet *)nidsToAllow
{
const unsigned char * ptr;
NSUInteger len;
// Gather the details for the CA cert (my cert) from
// OSX.
//
X509 * x509_mycert = NULL;
SecIdentityRef identityRef = [self secIdentityRef];
if (!identityRef)
return nil;
SecCertificateRef certificateRef = [self secCertificateRef];
if (!certificateRef)
return nil;
CFDataRef certAsDer = SecCertificateCopyData(certificateRef);
if (!certAsDer)
return nil;
// Jump over the fence to OpenSSL - and create
// an X509 version.
//
ptr = CFDataGetBytePtr(certAsDer);
len = CFDataGetLength(certAsDer);
if (!(d2i_X509(&x509_mycert, &ptr, len)))
return nil;
// And likewise for the CSR.
//
ptr = (const unsigned char *)[derCSR bytes];
len = [derCSR length];
X509_REQ *req = NULL;
if (!(d2i_X509_REQ(&req, &ptr, len)))
return nil;
// Copy the CSR into a an actual x509 tenative
// structure; i.e. the cert we'll issue signed.
//
X509 * x509_to_sign = X509_new();
assert(X509_set_subject_name(x509_to_sign,req->req_info->subject));
assert(X509_set_issuer_name(x509_to_sign, X509_get_subject_name(x509_mycert)));
EVP_PKEY * pubkey_csr = X509_REQ_get_pubkey(req);
X509_set_pubkey(x509_to_sign,pubkey_csr);
EVP_PKEY_free(pubkey_csr);
X509_gmtime_adj(X509_get_notBefore(x509_to_sign),0L);
X509_gmtime_adj(X509_get_notAfter(x509_to_sign),(long)floor(60*60*24*days));
if (nidsToAllow && [nidsToAllow count]) {
// Faily blindly copy all known extensions.
//
for(int i = X509_get_ext_count(x509_to_sign); i > 0; i--) {
X509_EXTENSION * ext = X509_get_ext(x509_to_sign,i-i);
int nid = OBJ_obj2nid(ext->object);
if ([nidsToAllow containsObject:[NSNumber numberWithInt:nid]]) {
// NSLog(@"Keeping %s at %d", OBJ_nid2sn(nid),i-i);
continue;
}
// NSLog(@"Killing %s at %d", OBJ_nid2sn(nid),i-1);
X509_delete_ext(x509_to_sign, i-i);
}
} else {
// wipe them all.
//
while (X509_get_ext_count(x509_to_sign) > 0) {
X509_delete_ext(x509_to_sign, 0);
}
};
// Set a random serial.
//
ASN1_INTEGER *bs = ASN1_INTEGER_new();
long rnd = 0;
if (!(RAND_bytes((unsigned char *)&rnd, sizeof(rnd))))
return nil;
rnd = labs(rnd);
ASN1_INTEGER_set(bs, rnd);
if (!((X509_set_serialNumber(x509_to_sign,bs))))
return nil;
ASN1_INTEGER_free(bs);
// Force v3
//
X509V3_CTX ctx2;
X509_set_version(x509_to_sign,2); /* version 3 certificate */
X509V3_set_ctx(&ctx2, x509_mycert, x509_to_sign, NULL, NULL, 0);
// Pull in additional x509v3 sections.
//
if (DBA) {
assert(X509V3_set_nconf(&ctx2, conf));
assert(X509V3_EXT_add_nconf(conf, &ctx2, section, x509_to_sign));
}
// Specify signature type.
//
x509_to_sign->cert_info->signature->algorithm = OBJ_nid2obj(NID_sha1WithRSAEncryption);
// Construct the ASN.1 blob which contains all the information
// we are going to sign.
//
const ASN1_ITEM * it = ASN1_ITEM_rptr(X509_CINF);
unsigned char *buf_in=NULL;
ASN1_VALUE * asn = (ASN1_VALUE *)(x509_to_sign->cert_info);
int inl = ASN1_item_i2d(asn,&buf_in, it);
// Small area to hold the signature on the SHA1 hash.
//
size_t sigLen = SecKeyGetBlockSize(privateKey);
uint8_t * sig = (uint8_t *)malloc(sigLen * sizeof(uint8_t));
memset((void*)sig, 0, sigLen);
#if TARGET_OS_IPHONE
// IPhone Way of doing it - where we need to construct the
// SHA1 of the 'to sign' area ourselves. As SecKeyRawSign
// does not seem to handly anything beyond a SHA1.
//
NSData * buffToSign = [NSData dataWithBytes:buf_in length:inl];
NSData * buffSha1ToSign = [buffToSign sha1];
size_t sigLenUsed = sigLen;
OSStatus status = SecKeyRawSign(privateKey, kSecPaddingPKCS1SHA1, [buffSha1ToSign bytes], [buffSha1ToSign length], sig, &sigLenUsed);
assert(status == noErr);
assert(sigLenUsed == sigLen);
#else
// MacOSX offical way of doing this - which seems to do the SHA1 fun,
// padding and games deeper down; and where we simply pass the blob.
//
CFErrorRef error = NULL;
SecTransformRef signer = SecSignTransformCreate(privateKey, &error);
if (error) { CFShow(error); assert(0); };
NSData * blockToSign = [NSData dataWithBytes:buf_in length:inl];
SecTransformSetAttribute(signer, kSecTransformInputAttributeName,
(__bridge CFTypeRef) blockToSign, &error);
if (error) { CFShow(error); assert(0); };
CFDataRef signature = SecTransformExecute(signer, &error);
if (error) { CFShow(error); assert(0); };
assert(sigLen == CFDataGetLength(signature));
bcopy(CFDataGetBytePtr(signature), sig, sigLen);
#endif
// Wrap up the rest of the block with the bits and bobs needed to
// create a valid ASN1 block to share as a PEM or DER. Which most
// crucially is about copying the just created signature into it.
//
x509_to_sign->sig_alg->algorithm = OBJ_nid2obj(NID_sha1WithRSAEncryption);
x509_to_sign->signature->data = sig;
x509_to_sign->signature->length = sigLen;
x509_to_sign->signature->flags&= ~(ASN1_STRING_FLAG_BITS_LEFT|0x07);
x509_to_sign->signature->flags|=ASN1_STRING_FLAG_BITS_LEFT;
unsigned char * derbuff = NULL;
int derlen = i2d_X509(x509_to_sign, &derbuff);
NSData * signedDer = [NSData dataWithBytes:derbuff length:derlen];
free(sig);
OPENSSL_free(x509_to_sign);
OPENSSL_free(x509_mycert);
return signedDer;
}