在iOS中使用RSA加密解密，需要用到.der和.p12后缀格式的文件，其中.der格式的文件存放的是公钥（Public key）用于加密，.p12格式的文件存放的是私钥（Private key）用于解密. 首先需要先生成这些文件，然后再将文件导入工程使用，不多说，开始做！ 一、使用openssl生成所需秘钥文件 生成环境是在mac系统下，使用openssl进行生成，首先打开终端，按下面这些步骤依次来做： 1. 生成模长为1024bit的私钥文件private_key.pem openssl genrsa -out private_key.pem 1024 2. 生成证书请求文件rsaCertReq.csr openssl req -new -key private_key.pem -out rsaCerReq.csr 注意：这一步会提示输入国家、省份、mail等信息，可以根据实际情况填写，或者全部不用填写，直接全部敲回车. 3. 生成证书rsaCert.crt，并设置有效时间为1年 openssl x509 -req -days 3650 -in rsaCerReq.csr -signkey private_key.pem -out rsaCert.crt 4. 生成供iOS使用的公钥文件public_key.der openssl x509 -outform der -in rsaCert.crt -out public_key.der 5. 生成供iOS使用的私钥文件private_key.p12 openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt 注意：这一步会提示给私钥文件设置密码，直接输入想要设置密码即可，然后敲回车，然后再验证刚才设置的密码，再次输入密码，然后敲回车，完毕！ 在解密时，private_key.p12文件需要和这里设置的密码配合使用，因此需要牢记此密码. 6. 生成供Java使用的公钥rsa_public_key.pem openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout 7. 生成供Java使用的私钥pkcs8_private_key.pem openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt 全部执行成功后，会生成如下文件，其中public_key.der和private_key.p12就是iOS需要用到的文件，如下图： 生成的文件 二、将文件导入工程使用 1.新建工程, 并导入Security.framework框架, 如下图: 新建工程并添加框架 2.导入秘钥文件 导入.der和.p12格式的秘钥文件, 如下图: 导入秘钥文件 3.新建用于加密、解密的类RSAEncryptor, 并实现相关方法 新建RSAEncryptor类, 如下图: 新建用于加密解密的类 下面开始上代码, 可以直接复制过去用: RSAEncryptor.h代码如下: #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:@" " withString:@""]; key = [key stringByReplacingOccurrencesOfString:@" " withString:@""]; key = [key stringByReplacingOccurrencesOfString:@" " 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++] != ' ') 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:@" " withString:@""]; key = [key stringByReplacingOccurrencesOfString:@" " withString:@""]; key = [key stringByReplacingOccurrencesOfString:@" " 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 4. 测试加密、解密 首先先测试使用.der和.p12秘钥文件进行加密、解密, 在ViewController.m中进行测试, 代码如下: #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 运行后, 输出信息如下: 输出结果 可以看到已经可以成功加密、解密了. 下面接着测试使用秘钥字符串进行加密、解密, 那么秘钥字符串从哪里来? 可以来这里:http://web.chacuo.net/netrsakeypair, 这是一个在线生成RSA秘钥的网站, 生成公钥和秘钥后, 复制出来用于测试. 然后在ViewController.m中使用RSAEntryptor.h头文件中对应的加密方法进行加密, ViewController.m中代码如下: #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:@"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"]); } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } @end