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加密解密需要生成公鑰、私鑰文件步驟

1.打開終端 輸入

openssl

5F88AA4A-3913-4CBC-9307-00ED47557FCD.png

2.生成私鑰文件
輸入：

genrsa -out private_key.pem 1024

genrsa:指定了生成了算法使用RSA
-out:后面的參數表示生成的key的輸入文件
1024:表示的是生成key的長度,單位字節(bits)

EC31F55E-1142-49CD-A3B9-BBF435950F27.png

D9AD9E8E-43EE-4352-A2CC-A3787076AC51.png

若找不到該文件可全局搜索該名字

3.創建證書請求
輸入：

req -new -key private_key.pem -out rsaCertReq.csr

會讓輸入一些信息，可填可不填

4405C579-7C91-4F72-A8C8-B23727AC9F4F.png

4.生成證書并簽名，有效期10年
輸入：

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

41C14307-493D-417B-967E-8CA6196A1344.png

5.轉換格式 將 PEM 格式文件 轉換成 DER 格式 ，此為公鑰文件，項目中用得到
輸入：

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

0DBCD317-806A-4779-BA19-8E2C060CEEA0.png

9E1FB8E4-DBAA-425F-8879-3A839A09234A.png

6.導出 P12 文件，此為私鑰文件。項目中用得到
輸入：

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

會讓輸入密碼，記住該密碼，程序中會用得到

64F45FBA-74A6-4BF5-A4E1-88D324057E0B.png

7.給Java創建 rsa_public_key.pem
輸入：

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

8.給Java創建 pkcs8_private_key.pem
輸入：

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

CC811457-3CDB-43C7-ACA1-3150602A845F.png

證書已經創建完畢

DBB2A1A7-E042-4860-BF39-FFC524D08F8F.png

iOS使用證書

先請你把 public_key.der 和 private_key.p12 拖進你的Xcode項目里去
同時引入 Security.framework 以及 NSData+Base64.h/m （github可下載）到項目里。

為了使用方便，可引入工具類，代碼如下：

@interface RSAEncryptor : NSObject

-(void) loadPublicKeyFromFile: (NSString*) derFilePath;
-(void) loadPublicKeyFromData: (NSData*) derData;

-(void) loadPrivateKeyFromFile: (NSString*) p12FilePath password:(NSString*)p12Password;
-(void) loadPrivateKeyFromData: (NSData*) p12Data password:(NSString*)p12Password;


-(NSString*) rsaEncryptString:(NSString*)string;
-(NSData*) rsaEncryptData:(NSData*)data ;

-(NSString*) rsaDecryptString:(NSString*)string;
-(NSData*) rsaDecryptData:(NSData*)data;


+(void) setSharedInstance: (RSAEncryptor*)instance;
+(RSAEncryptor*) sharedInstance;


@end

#import "RSAEncryptor.h"
#import "Base64.h"
#import <Security/Security.h>

@implementation RSAEncryptor
{
    SecKeyRef publicKey;
    
    SecKeyRef privateKey;
}
-(void)dealloc
{
    CFRelease(publicKey);
    CFRelease(privateKey);
}



-(SecKeyRef) getPublicKey {
    return publicKey;
}

-(SecKeyRef) getPrivateKey {
    return privateKey;
}



-(void) loadPublicKeyFromFile: (NSString*) derFilePath
{
    NSData *derData = [[NSData alloc] initWithContentsOfFile:derFilePath];
    [self loadPublicKeyFromData: derData];
}
-(void) loadPublicKeyFromData: (NSData*) derData
{
    publicKey = [self getPublicKeyRefrenceFromeData: derData];
}

-(void) loadPrivateKeyFromFile: (NSString*) p12FilePath password:(NSString*)p12Password
{
    NSData *p12Data = [NSData dataWithContentsOfFile:p12FilePath];
    [self loadPrivateKeyFromData: p12Data password:p12Password];
}

-(void) loadPrivateKeyFromData: (NSData*) p12Data password:(NSString*)p12Password
{
    privateKey = [self getPrivateKeyRefrenceFromData: p12Data password: p12Password];
}




#pragma mark - Private Methods

-(SecKeyRef) getPublicKeyRefrenceFromeData: (NSData*)derData
{
    SecCertificateRef myCertificate = SecCertificateCreateWithData(kCFAllocatorDefault, (__bridge CFDataRef)derData);
    SecPolicyRef myPolicy = SecPolicyCreateBasicX509();
    SecTrustRef myTrust;
    OSStatus status = SecTrustCreateWithCertificates(myCertificate,myPolicy,&myTrust);
    SecTrustResultType trustResult;
    if (status == noErr) {
        status = SecTrustEvaluate(myTrust, &trustResult);
    }
    SecKeyRef securityKey = SecTrustCopyPublicKey(myTrust);
    CFRelease(myCertificate);
    CFRelease(myPolicy);
    CFRelease(myTrust);
    
    return securityKey;
}


-(SecKeyRef) getPrivateKeyRefrenceFromData: (NSData*)p12Data password:(NSString*)password
{
    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;
}



#pragma mark - Encrypt

-(NSString*) rsaEncryptString:(NSString*)string {
    NSData* data = [string dataUsingEncoding:NSUTF8StringEncoding];
    NSData* encryptedData = [self rsaEncryptData: data];
    NSString* base64EncryptedString = [encryptedData base64EncodedString];
    return base64EncryptedString;
}

// 加密的大小受限于SecKeyEncrypt函數，SecKeyEncrypt要求明文和密鑰的長度一致，如果要加密更長的內容，需要把內容按密鑰長度分成多份，然后多次調用SecKeyEncrypt來實現
-(NSData*) rsaEncryptData:(NSData*)data {
    SecKeyRef key = [self getPublicKey];
    size_t cipherBufferSize = SecKeyGetBlockSize(key);
    uint8_t *cipherBuffer = malloc(cipherBufferSize * sizeof(uint8_t));
    size_t blockSize = cipherBufferSize - 11;       // 分段加密
    size_t blockCount = (size_t)ceil([data length] / (double)blockSize);
    NSMutableData *encryptedData = [[NSMutableData alloc] init] ;
    for (int i=0; i<blockCount; i++) {
        int bufferSize = MIN(blockSize,[data length] - i * blockSize);
        NSData *buffer = [data subdataWithRange:NSMakeRange(i * blockSize, bufferSize)];
        OSStatus status = SecKeyEncrypt(key, kSecPaddingPKCS1, (const uint8_t *)[buffer bytes], [buffer length], cipherBuffer, &cipherBufferSize);
        if (status == noErr){
            NSData *encryptedBytes = [[NSData alloc] initWithBytes:(const void *)cipherBuffer length:cipherBufferSize];
            [encryptedData appendData:encryptedBytes];
        }else{
            if (cipherBuffer) {
                free(cipherBuffer);
            }
            return nil;
        }
    }
    if (cipherBuffer){
        free(cipherBuffer);
    }
    return encryptedData;
}




#pragma mark - Decrypt

-(NSString*) rsaDecryptString:(NSString*)string {
    NSData *data = [NSData dataWithBase64EncodedString:string];
    //    NSData* data = [NSData dataFromBase64String: string];
    NSData* decryptData = [self rsaDecryptData: data];
    NSString* result = [[NSString alloc] initWithData: decryptData encoding:NSUTF8StringEncoding];
    return result;
}

-(NSData*) rsaDecryptData:(NSData*)data {
    SecKeyRef key = [self getPrivateKey];
    size_t cipherLen = [data length];
    void *cipher = malloc(cipherLen);
    [data getBytes:cipher length:cipherLen];
    size_t plainLen = SecKeyGetBlockSize(key) - 12;
    void *plain = malloc(plainLen);
    OSStatus status = SecKeyDecrypt(key, kSecPaddingPKCS1, cipher, cipherLen, plain, &plainLen);
    
    if (status != noErr) {
        return nil;
    }
    
    NSData *decryptedData = [[NSData alloc] initWithBytes:(const void *)plain length:plainLen];
    
    return decryptedData;
}


#pragma mark - Class Methods

static RSAEncryptor* sharedInstance = nil;

+(void) setSharedInstance: (RSAEncryptor*)instance
{
    sharedInstance = instance;
}

+(RSAEncryptor*) sharedInstance
{
    return sharedInstance;
}
@end

即可使用RSA加密解密

//配置秘鑰
    RSAEncryptor* rsaEncryptor = [[RSAEncryptor alloc] init];
    NSString* publicKeyPath = [[NSBundle mainBundle] pathForResource:@"public_key" ofType:@"der"];
    NSString* privateKeyPath = [[NSBundle mainBundle] pathForResource:@"private_key" ofType:@"p12"];
    [rsaEncryptor loadPublicKeyFromFile: publicKeyPath];
    [rsaEncryptor loadPrivateKeyFromFile: privateKeyPath password:@"生成p12時的密碼"];    // 換成你生成p12時的密碼
    //字符串RSA加密
    NSString *string = @"RSA加密字符串";
    NSString* restrinBASE64STRING = [rsaEncryptor rsaEncryptString:string];
    NSLog(@"加密后：==== %@", restrinBASE64STRING);
    
    
    //字符串RSA解密
    NSString* decryptString = [rsaEncryptor rsaDecryptString: restrinBASE64STRING];
    NSLog(@"解密后：==== %@", decryptString);

運行結果

6307CA8C-8B57-46FA-AC35-29F66C24CC77.png

如果沒有解決問題，推薦看下一篇文章
RSA 加密、解密(服務器給公鑰，剩下的自己搞)
http://www.lxweimin.com/p/f4497d19f336