`+ (NSData *)decryptData:(NSData *)data privateKey:(NSString *)privKey{
if(!data || !privKey){
return nil;
}
SecKeyRef keyRef = [RSA addPrivateKey:privKey];
if(!keyRef){
return nil;
}
return [RSA decryptData:data withKeyRef:keyRef];
} + (NSData *)decryptData:(NSData *)cipherData withKeyRef:(SecKeyRef) keyRef{
size_t plainBufferSize = SecKeyGetBlockSize(keyRef);
NSLog(@"plainBufferSize = %zd", plainBufferSize);
uint8_t *plainBuffer = malloc(plainBufferSize * sizeof(uint8_t));
// 计算数据段最大长度及数据段的个数
double totalLength = [cipherData length];
size_t blockSize = plainBufferSize;
size_t blockCount = (size_t)ceil(totalLength / blockSize);
NSMutableData *decryptedData = [NSMutableData data];
// 分段解密
for (int i = 0; i < blockCount; i++) {
NSUInteger loc = i * blockSize;
// 数据段的实际大小。最后一段可能比blockSize小。
int dataSegmentRealSize = MIN(blockSize, totalLength - loc);
// 截取需要解密的数据段
NSData *dataSegment = [cipherData subdataWithRange:NSMakeRange(loc, dataSegmentRealSize)];
OSStatus status = SecKeyDecrypt(keyRef, kSecPaddingPKCS1, (const uint8_t *)[dataSegment bytes], dataSegmentRealSize, plainBuffer, &plainBufferSize);
if (status == errSecSuccess) {
NSData *decryptedDataSegment = [[NSData alloc] initWithBytes:(const void *)plainBuffer length:plainBufferSize];
[decryptedData appendData:decryptedDataSegment];
} else {
if (plainBuffer) {
free(plainBuffer);
}
return nil;
}
}
if (plainBuffer) {
free(plainBuffer);
}
return decryptedData;`
