iOS中使用RSA加密详解

#import <Foundation/Foundation.h>
@interface RSAEncryptor : NSObject
/**
 * 加密方法
 *
 * @param str 需要加密的字符串
 * @param path '.der'格式的公钥文件路径
 */
  (NSString *)encryptString:(NSString *)str publicKeyWithContentsOfFile:(NSString *)path;
/**
 * 解密方法
 *
 * @param str 需要解密的字符串
 * @param path '.p12'格式的私钥文件路径
 * @param password 私钥文件密码
 */
  (NSString *)decryptString:(NSString *)str privateKeyWithContentsOfFile:(NSString *)path password:(NSString *)password;
/**
 * 加密方法
 *
 * @param str 需要加密的字符串
 * @param pubKey 公钥字符串
 */
  (NSString *)encryptString:(NSString *)str publicKey:(NSString *)pubKey;
/**
 * 解密方法
 *
 * @param str 需要解密的字符串
 * @param privKey 私钥字符串
 */
  (NSString *)decryptString:(NSString *)str privateKey:(NSString *)privKey;
@end
RSAEncryptor.m代码如下:
#import "RSAEncryptor.h"
#import <Security/Security.h>
@implementation RSAEncryptor
static NSString *base64_encode_data(NSData *data){
 data = [data base64EncodedDataWithOptions:0];
 NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 return ret;
}
static NSData *base64_decode(NSString *str){
 NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
 return data;
}
#pragma mark - 使用'.der'公钥文件加密
//加密
  (NSString *)encryptString:(NSString *)str publicKeyWithContentsOfFile:(NSString *)path{
 if (!str || !path) return nil;
 return [self encryptString:str publicKeyRef:[self getPublicKeyRefWithContentsOfFile:path]];
}
//获取公钥
  (SecKeyRef)getPublicKeyRefWithContentsOfFile:(NSString *)filePath{
 NSData *certData = [NSData dataWithContentsOfFile:filePath];
 if (!certData) {
 return nil;
 }
 SecCertificateRef cert = SecCertificateCreateWithData(NULL, (CFDataRef)certData);
 SecKeyRef key = NULL;
 SecTrustRef trust = NULL;
 SecPolicyRef policy = NULL;
 if (cert != NULL) {
 policy = SecPolicyCreateBasicX509();
 if (policy) {
  if (SecTrustCreateWithCertificates((CFTypeRef)cert, policy, &trust) == noErr) {
  SecTrustResultType result;
  if (SecTrustEvaluate(trust, &result) == noErr) {
   key = SecTrustCopyPublicKey(trust);
  }
  }
 }
 }
 if (policy) CFRelease(policy);
 if (trust) CFRelease(trust);
 if (cert) CFRelease(cert);
 return key;
}
  (NSString *)encryptString:(NSString *)str publicKeyRef:(SecKeyRef)publicKeyRef{
 if(![str dataUsingEncoding:NSUTF8StringEncoding]){
 return nil;
 }
 if(!publicKeyRef){
 return nil;
 }
 NSData *data = [self encryptData:[str dataUsingEncoding:NSUTF8StringEncoding] withKeyRef:publicKeyRef];
 NSString *ret = base64_encode_data(data);
 return ret;
}
#pragma mark - 使用'.12'私钥文件解密
//解密
  (NSString *)decryptString:(NSString *)str privateKeyWithContentsOfFile:(NSString *)path password:(NSString *)password{
 if (!str || !path) return nil;
 if (!password) password = @"";
 return [self decryptString:str privateKeyRef:[self getPrivateKeyRefWithContentsOfFile:path password:password]];
}
//获取私钥
  (SecKeyRef)getPrivateKeyRefWithContentsOfFile:(NSString *)filePath password:(NSString*)password{
 NSData *p12Data = [NSData dataWithContentsOfFile:filePath];
 if (!p12Data) {
 return nil;
 }
 SecKeyRef privateKeyRef = NULL;
 NSMutableDictionary * options = [[NSMutableDictionary alloc] init];
 [options setObject: password forKey:(__bridge id)kSecImportExportPassphrase];
 CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
 OSStatus securityError = SecPKCS12Import((__bridge CFDataRef) p12Data, (__bridge CFDictionaryRef)options, &items);
 if (securityError == noErr && CFArrayGetCount(items) > 0) {
 CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
 SecIdentityRef identityApp = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
 securityError = SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);
 if (securityError != noErr) {
  privateKeyRef = NULL;
 }
 }
 CFRelease(items);
 return privateKeyRef;
}
  (NSString *)decryptString:(NSString *)str privateKeyRef:(SecKeyRef)privKeyRef{
 NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
 if (!privKeyRef) {
 return nil;
 }
 data = [self decryptData:data withKeyRef:privKeyRef];
 NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 return ret;
}
#pragma mark - 使用公钥字符串加密
/* START: Encryption with RSA public key */
//使用公钥字符串加密
  (NSString *)encryptString:(NSString *)str publicKey:(NSString *)pubKey{
 NSData *data = [self encryptData:[str dataUsingEncoding:NSUTF8StringEncoding] publicKey:pubKey];
 NSString *ret = base64_encode_data(data);
 return ret;
}
  (NSData *)encryptData:(NSData *)data publicKey:(NSString *)pubKey{
 if(!data || !pubKey){
 return nil;
 }
 SecKeyRef keyRef = [self addPublicKey:pubKey];
 if(!keyRef){
 return nil;
 }
 return [self encryptData:data withKeyRef:keyRef];
}
  (SecKeyRef)addPublicKey:(NSString *)key{
 NSRange spos = [key rangeOfString:@"-----BEGIN PUBLIC KEY-----"];
 NSRange epos = [key rangeOfString:@"-----END PUBLIC KEY-----"];
 if(spos.location != NSNotFound && epos.location != NSNotFound){
 NSUInteger s = spos.location   spos.length;
 NSUInteger e = epos.location;
 NSRange range = NSMakeRange(s, e-s);
 key = [key substringWithRange:range];
 }
 key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
 key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
 key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
 key = [key stringByReplacingOccurrencesOfString:@" " withString:@""];
 // This will be base64 encoded, decode it.
 NSData *data = base64_decode(key);
 data = [self stripPublicKeyHeader:data];
 if(!data){
 return nil;
 }
 //a tag to read/write keychain storage
 NSString *tag = @"RSAUtil_PubKey";
 NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];
 // Delete any old lingering key with the same tag
 NSMutableDictionary *publicKey = [[NSMutableDictionary alloc] init];
 [publicKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
 [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
 [publicKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
 SecItemDelete((__bridge CFDictionaryRef)publicKey);
 // Add persistent version of the key to system keychain
 [publicKey setObject:data forKey:(__bridge id)kSecValueData];
 [publicKey setObject:(__bridge id) kSecAttrKeyClassPublic forKey:(__bridge id)
 kSecAttrKeyClass];
 [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
 kSecReturnPersistentRef];
 CFTypeRef persistKey = nil;
 OSStatus status = SecItemAdd((__bridge CFDictionaryRef)publicKey, &persistKey);
 if (persistKey != nil){
 CFRelease(persistKey);
 }
 if ((status != noErr) && (status != errSecDuplicateItem)) {
 return nil;
 }
 [publicKey removeObjectForKey:(__bridge id)kSecValueData];
 [publicKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
 [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
 [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
 // Now fetch the SecKeyRef version of the key
 SecKeyRef keyRef = nil;
 status = SecItemCopyMatching((__bridge CFDictionaryRef)publicKey, (CFTypeRef *)&keyRef);
 if(status != noErr){
 return nil;
 }
 return keyRef;
}
  (NSData *)stripPublicKeyHeader:(NSData *)d_key{
 // Skip ASN.1 public key header
 if (d_key == nil) return(nil);
 unsigned long len = [d_key length];
 if (!len) return(nil);
 unsigned char *c_key = (unsigned char *)[d_key bytes];
 unsigned int idx = 0;
 if (c_key[idx  ] != 0x30) return(nil);
 if (c_key[idx] > 0x80) idx  = c_key[idx] - 0x80   1;
 else idx  ;
 // PKCS #1 rsaEncryption szOID_RSA_RSA
 static unsigned char seqiod[] =
 { 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
 0x01, 0x05, 0x00 };
 if (memcmp(&c_key[idx], seqiod, 15)) return(nil);
 idx  = 15;
 if (c_key[idx  ] != 0x03) return(nil);
 if (c_key[idx] > 0x80) idx  = c_key[idx] - 0x80   1;
 else idx  ;
 if (c_key[idx  ] != '\0') return(nil);
 // Now make a new NSData from this buffer
 return ([NSData dataWithBytes:&c_key[idx] length:len - idx]);
}
  (NSData *)encryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
 const uint8_t *srcbuf = (const uint8_t *)[data bytes];
 size_t srclen = (size_t)data.length;
 size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
 void *outbuf = malloc(block_size);
 size_t src_block_size = block_size - 11;
 NSMutableData *ret = [[NSMutableData alloc] init];
 for(int idx=0; idx<srclen; idx =src_block_size){
 //NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
 size_t data_len = srclen - idx;
 if(data_len > src_block_size){
  data_len = src_block_size;
 }
 size_t outlen = block_size;
 OSStatus status = noErr;
 status = SecKeyEncrypt(keyRef,
    kSecPaddingPKCS1,
    srcbuf   idx,
    data_len,
    outbuf,
    &outlen
    );
 if (status != 0) {
  NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
  ret = nil;
  break;
 }else{
  [ret appendBytes:outbuf length:outlen];
 }
 }
 free(outbuf);
 CFRelease(keyRef);
 return ret;
}
/* END: Encryption with RSA public key */
#pragma mark - 使用私钥字符串解密
/* START: Decryption with RSA private key */
//使用私钥字符串解密
  (NSString *)decryptString:(NSString *)str privateKey:(NSString *)privKey{
 if (!str) return nil;
 NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
 data = [self decryptData:data privateKey:privKey];
 NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 return ret;
}
  (NSData *)decryptData:(NSData *)data privateKey:(NSString *)privKey{
 if(!data || !privKey){
 return nil;
 }
 SecKeyRef keyRef = [self addPrivateKey:privKey];
 if(!keyRef){
 return nil;
 }
 return [self decryptData:data withKeyRef:keyRef];
}
  (SecKeyRef)addPrivateKey:(NSString *)key{
 NSRange spos = [key rangeOfString:@"-----BEGIN RSA PRIVATE KEY-----"];
 NSRange epos = [key rangeOfString:@"-----END RSA PRIVATE KEY-----"];
 if(spos.location != NSNotFound && epos.location != NSNotFound){
 NSUInteger s = spos.location   spos.length;
 NSUInteger e = epos.location;
 NSRange range = NSMakeRange(s, e-s);
 key = [key substringWithRange:range];
 }
 key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
 key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
 key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
 key = [key stringByReplacingOccurrencesOfString:@" " withString:@""];
 // This will be base64 encoded, decode it.
 NSData *data = base64_decode(key);
 data = [self stripPrivateKeyHeader:data];
 if(!data){
 return nil;
 }
 //a tag to read/write keychain storage
 NSString *tag = @"RSAUtil_PrivKey";
 NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];
 // Delete any old lingering key with the same tag
 NSMutableDictionary *privateKey = [[NSMutableDictionary alloc] init];
 [privateKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
 [privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
 [privateKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
 SecItemDelete((__bridge CFDictionaryRef)privateKey);
 // Add persistent version of the key to system keychain
 [privateKey setObject:data forKey:(__bridge id)kSecValueData];
 [privateKey setObject:(__bridge id) kSecAttrKeyClassPrivate forKey:(__bridge id)
 kSecAttrKeyClass];
 [privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
 kSecReturnPersistentRef];
 CFTypeRef persistKey = nil;
 OSStatus status = SecItemAdd((__bridge CFDictionaryRef)privateKey, &persistKey);
 if (persistKey != nil){
 CFRelease(persistKey);
 }
 if ((status != noErr) && (status != errSecDuplicateItem)) {
 return nil;
 }
 [privateKey removeObjectForKey:(__bridge id)kSecValueData];
 [privateKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
 [privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
 [privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
 // Now fetch the SecKeyRef version of the key
 SecKeyRef keyRef = nil;
 status = SecItemCopyMatching((__bridge CFDictionaryRef)privateKey, (CFTypeRef *)&keyRef);
 if(status != noErr){
 return nil;
 }
 return keyRef;
}
  (NSData *)stripPrivateKeyHeader:(NSData *)d_key{
 // Skip ASN.1 private key header
 if (d_key == nil) return(nil);
 unsigned long len = [d_key length];
 if (!len) return(nil);
 unsigned char *c_key = (unsigned char *)[d_key bytes];
 unsigned int idx = 22; //magic byte at offset 22
 if (0x04 != c_key[idx  ]) return nil;
 //calculate length of the key
 unsigned int c_len = c_key[idx  ];
 int det = c_len & 0x80;
 if (!det) {
 c_len = c_len & 0x7f;
 } else {
 int byteCount = c_len & 0x7f;
 if (byteCount   idx > len) {
  //rsa length field longer than buffer
  return nil;
 }
 unsigned int accum = 0;
 unsigned char *ptr = &c_key[idx];
 idx  = byteCount;
 while (byteCount) {
  accum = (accum << 8)   *ptr;
  ptr  ;
  byteCount--;
 }
 c_len = accum;
 }
 // Now make a new NSData from this buffer
 return [d_key subdataWithRange:NSMakeRange(idx, c_len)];
}
  (NSData *)decryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
 const uint8_t *srcbuf = (const uint8_t *)[data bytes];
 size_t srclen = (size_t)data.length;
 size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
 UInt8 *outbuf = malloc(block_size);
 size_t src_block_size = block_size;
 NSMutableData *ret = [[NSMutableData alloc] init];
 for(int idx=0; idx<srclen; idx =src_block_size){
 //NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
 size_t data_len = srclen - idx;
 if(data_len > src_block_size){
  data_len = src_block_size;
 }
 size_t outlen = block_size;
 OSStatus status = noErr;
 status = SecKeyDecrypt(keyRef,
    kSecPaddingNone,
    srcbuf   idx,
    data_len,
    outbuf,
    &outlen
    );
 if (status != 0) {
  NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
  ret = nil;
  break;
 }else{
  //the actual decrypted data is in the middle, locate it!
  int idxFirstZero = -1;
  int idxNextZero = (int)outlen;
  for ( int i = 0; i < outlen; i   ) {
  if ( outbuf[i] == 0 ) {
   if ( idxFirstZero < 0 ) {
   idxFirstZero = i;
   } else {
   idxNextZero = i;
   break;
   }
  }
  }
  [ret appendBytes:&outbuf[idxFirstZero 1] length:idxNextZero-idxFirstZero-1];
 }
 }
 free(outbuf);
 CFRelease(keyRef);
 return ret;
}
/* END: Decryption with RSA private key */
@end

#import "ViewController.h"
#import "RSAEncryptor.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
 [super viewDidLoad];
 //原始数据
 NSString *originalString = @"这是一段将要使用'.der'文件加密的字符串!";
 //使用.der和.p12中的公钥私钥加密解密
 NSString *public_key_path = [[NSBundle mainBundle] pathForResource:@"public_key.der" ofType:nil];
 NSString *private_key_path = [[NSBundle mainBundle] pathForResource:@"private_key.p12" ofType:nil];
 NSString *encryptStr = [RSAEncryptor encryptString:originalString publicKeyWithContentsOfFile:public_key_path];
 NSLog(@"加密前:%@", originalString);
 NSLog(@"加密后:%@", encryptStr);
 NSLog(@"解密后:%@", [RSAEncryptor decryptString:encryptStr privateKeyWithContentsOfFile:private_key_path password:@"123456"]);

}
- (void)didReceiveMemoryWarning {
 [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
}
@end

#import "ViewController.h"
#import "RSAEncryptor.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
 [super viewDidLoad];

 //原始数据
 NSString *originalString = @"这是一段将要使用'秘钥字符串'进行加密的字符串!";

 //使用字符串格式的公钥私钥加密解密
 NSString *encryptStr = [RSAEncryptor encryptString:originalString publicKey:@"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDTbZ6cNH9PgdF60aQKveLz3FTalyzHQwbp601y77SzmGHX3F5NoVUZbdK7UMdoCLK4FBziTewYD9DWvAErXZo9BFuI96bAop8wfl1VkZyyHTcznxNJFGSQd/B70/ExMgMBpEwkAAdyUqIjIdVGh1FQK/4acwS39YXwbS IlHsPSQIDAQAB"];
 NSLog(@"加密前:%@", originalString);
 NSLog(@"加密后:%@", encryptStr);
 NSLog(@"解密后:%@", [RSAEncryptor decryptString:encryptStr privateKey:@"MIICeAIBADANBgkqhkiG9w0BAQEFAASCAmIwggJeAgEAAoGBANNtnpw0f0 B0XrRpAq94vPcVNqXLMdDBunrTXLvtLOYYdfcXk2hVRlt0rtQx2gIsrgUHOJN7BgP0Na8AStdmj0EW4j3psCinzB XVWRnLIdNzOfE0kUZJB38HvT8TEyAwGkTCQAB3JSoiMh1UaHUVAr/hpzBLf1hfBtL4iUew9JAgMBAAECgYA1tGeQmAkqofga8XtwuxEWDoaDS9k0 EKeUoXGxzqoT/GyiihuIafjILFhoUA1ndf/yCQaG973sbTDhtfpMwqFNQq13 JAownslTjWgr7Hwf7qplYW92R7CU0v7wFfjqm1t/2FKU9JkHfaHfb7qqESMIbO/VMjER9o4tEx58uXDQJBAO0O4lnWDVjr1gN02cqvxPOtTY6DgFbQDeaAZF8obb6XqvCqGW/AVms3Bh8nVlUwdQ2K/xte8tHxjW9FtBQTLd8CQQDkUncO35gAqUF9Bhsdzrs7nO1J3VjLrM0ITrepqjqtVEvdXZc 1/UrkWVaIigWAXjQCVfmQzScdbznhYXPz5fXAkEAgB3KMRkhL4yNpmKRjhw ih ASeRCCSj6Sjfbhx4XaakYZmbXxnChg JB bZNz06YBFC5nLZM7y/n61o1f5/56wJBALw ZVzE6ly5L34114uG04W9x0HcFgau7MiJphFjgUdAtd/H9xfgE4odMRPUD3q9Me9LlMYK6MiKpfm4c2 3dzcCQQC8y37NPgpNEkd9smMwPpSEjPW41aMlfcKvP4Da3z7G5bGlmuICrva9YDAiaAyDGGCK8LxC8K6HpKrFgYrXkRtt"]);
}
- (void)didReceiveMemoryWarning {
 [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
}
@end