iOS中使用RSA加密詳解

2020-07-26 03:00:03

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在iOS中使用RSA加密解密，需要用到.der和.p12后綴格式的文件，其中.der格式的文件存放的是公鑰（Public key）用于加密，.p12格式的文件存放的是私鑰（Private key）用于解密. 首先需要先生成這些文件，然后再將文件導入工程使用，不多說，開始做！

一、使用openssl生成所需秘鑰文件

生成環境是在mac系統下，使用openssl進行生成，首先打開終端，按下面這些步驟依次來做：

1. 生成模長為1024bit的私鑰文件private_key.pem

openssl genrsa -out private_key.pem 1024

2. 生成證書請求文件rsaCertReq.csr

openssl req -new -key private_key.pem -out rsaCerReq.csr

注意：這一步會提示輸入國家、省份、mail等信息，可以根據實際情況填寫，或者全部不用填寫，直接全部敲回車.

3. 生成證書rsaCert.crt，并設置有效時間為1年

openssl x509 -req -days 3650 -in rsaCerReq.csr -signkey private_key.pem -out rsaCert.crt

4. 生成供iOS使用的公鑰文件public_key.der

openssl x509 -outform der -in rsaCert.crt -out public_key.der

5. 生成供iOS使用的私鑰文件private_key.p12

openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt

注意：這一步會提示給私鑰文件設置密碼，直接輸入想要設置密碼即可，然后敲回車，然后再驗證剛才設置的密碼，再次輸入密碼，然后敲回車，完畢！

在解密時，private_key.p12文件需要和這里設置的密碼配合使用，因此需要牢記此密碼.

6. 生成供Java使用的公鑰rsa_public_key.pem

openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout

7. 生成供Java使用的私鑰pkcs8_private_key.pem

openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt

全部執行成功后，會生成如下文件，其中public_key.der和private_key.p12就是iOS需要用到的文件，如下圖：

生成的文件

二、將文件導入工程使用

1.新建工程, 并導入Security.framework框架, 如下圖:

新建工程并添加框架

2.導入秘鑰文件

導入.der和.p12格式的秘鑰文件, 如下圖:

導入秘鑰文件

3.新建用于加密、解密的類RSAEncryptor, 并實現相關方法

新建RSAEncryptor類, 如下圖:

新建用于加密解密的類

下面開始上代碼, 可以直接復制過去用:

RSAEncryptor.h代碼如下:

#import <Foundation/Foundation.h>@interface RSAEncryptor : NSObject/** * 加密方法 * * @param str 需要加密的字符串 * @param path '.der'格式的公鑰文件路徑 */+ (NSString *)encryptString:(NSString *)str publicKeyWithContentsOfFile:(NSString *)path;/** * 解密方法 * * @param str 需要解密的字符串 * @param path '.p12'格式的私鑰文件路徑 * @param password 私鑰文件密碼 */+ (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 公鑰字符串 */+ (NSString *)encryptString:(NSString *)str publicKey:(NSString *)pubKey;/** * 解密方法 * * @param str 需要解密的字符串 * @param privKey 私鑰字符串 */+ (NSString *)decryptString:(NSString *)str privateKey:(NSString *)privKey;@endRSAEncryptor.m代碼如下:#import "RSAEncryptor.h"#import <Security/Security.h>@implementation RSAEncryptorstatic 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'公鑰文件加密//加密+ (NSString *)encryptString:(NSString *)str publicKeyWithContentsOfFile:(NSString *)path{ if (!str || !path) return nil; return [self encryptString:str publicKeyRef:[self getPublicKeyRefWithContentsOfFile:path]];}//獲取公鑰+ (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'私鑰文件解密//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]];}//獲取私鑰+ (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 - 使用公鑰字符串加密/* START: Encryption with RSA public key *///使用公鑰字符串加密+ (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 - 使用私鑰字符串解密/* START: Decryption with RSA private key *///使用私鑰字符串解密+ (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

4. 測試加密、解密

首先先測試使用.der和.p12秘鑰文件進行加密、解密, 在ViewController.m中進行測試, 代碼如下:

#import "ViewController.h"#import "RSAEncryptor.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; //原始數據 NSString *originalString = @"這是一段將要使用'.der'文件加密的字符串!"; //使用.der和.p12中的公鑰私鑰加密解密 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

運行后, 輸出信息如下:

輸出結果

可以看到已經可以成功加密、解密了.

下面接著測試使用秘鑰字符串進行加密、解密, 那么秘鑰字符串從哪里來? 可以來這里:http://web.chacuo.net/netrsakeypair, 這是一個在線生成RSA秘鑰的網站, 生成公鑰和秘鑰后, 復制出來用于測試. 然后在ViewController.m中使用RSAEntryptor.h頭文件中對應的加密方法進行加密, ViewController.m中代碼如下:

#import "ViewController.h"#import "RSAEncryptor.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; //原始數據 NSString *originalString = @"這是一段將要使用'秘鑰字符串'進行加密的字符串!"; //使用字符串格式的公鑰私鑰加密解密 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

運行后, 輸出信息如下: