通过 Security.framework 实现 RSA 加解密
Security API
iOS 上 Security.framework为我们提供了安全方面相关的 API。
Security.framework
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支持的 RSA KeySzie 大小 大小有：512，768，1024，2048位
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支持的 RSA 填充方式有三种：NOPadding,PKCS1,OAEP 三种方式 ，填充方式影响最大分组加密数据块的大小
kSecPaddingNone = 0, kSecPaddingPKCS1 = 1, kSecPaddingOAEP = 2, -
加密
iOS 2.0 - iOS 15.0OSStatus SecKeyEncrypt( SecKeyRef key, SecPadding padding, const uint8_t *plainText, size_t plainTextLen, uint8_t *cipherText, size_t *cipherTextLen) -
解密
iOS 2.0 - iOS 15.0OSStatus SecKeyDecrypt( SecKeyRef key, /* Private key */ SecPadding padding, /* kSecPaddingNone, kSecPaddingPKCS1, kSecPaddingOAEP */ const uint8_t *cipherText, size_t cipherTextLen, /* length of cipherText */ uint8_t *plainText, size_t *plainTextLen)
openssl 生成 RSA 密钥
由于在项目开发中，一般使用服务器提供的密钥对，在本地调试时可使用 openssl 生成
#!/usr/bin/env bash
echo "Generating RSA key pair ..."
echo "1024 RSA key: private_key.pem"
openssl genrsa -out private_key.pem 1024
echo "create certification require file: rsaCertReq.csr"
openssl req -new -key private_key.pem -out rsaCertReq.csr
echo "create certification using x509: rsaCert.crt"
openssl x509 -req -days 3650 -in rsaCertReq.csr -signkey private_key.pem -out rsaCert.crt
echo "create public_key.der For IOS"
openssl x509 -outform der -in rsaCert.crt -out public_key.der
echo "create private_key.p12 For IOS. Please remember your password. The password will be used in iOS."
openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt
echo "create rsa_public_key.pem For Java"
openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout
echo "create pkcs8_private_key.pem For Java"
openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt
echo "finished."
加载公钥
在加密过程之前，我们需要先获取公钥进行存储，这里是通过 .der 文件 加载到 类型为 SecKeyRef 的公钥数据，并进行存储。
- (SecKeyRef)loadPublicKey:(NSString *)publicKeyPath {
NSAssert(publicKeyPath.length != 0, @"公钥路径为空");
// 从一个 DER 表示的证书创建一个证书对象
NSData *certificateData = [NSData dataWithContentsOfFile:publicKeyPath];
SecCertificateRef certificateRef = SecCertificateCreateWithData(kCFAllocatorDefault, (__bridge CFDataRef)certificateData);
NSAssert(certificateRef != NULL, @"公钥文件错误");
// 返回一个默认 X509 策略的公钥对象，使用之后需要调用 CFRelease 释放
SecPolicyRef policyRef = SecPolicyCreateBasicX509();
// 包含信任管理信息的结构体
SecTrustRef trustRef;
// 基于证书和策略创建一个信任管理对象
OSStatus status = SecTrustCreateWithCertificates(certificateRef, policyRef, &trustRef);
NSAssert(status == errSecSuccess, @"创建信任管理对象失败");
// 信任结果
SecTrustResultType trustResult;
// 评估指定证书和策略的信任管理是否有效
status = SecTrustEvaluate(trustRef, &trustResult);
NSAssert(status == errSecSuccess, @"信任评估失败");
// 评估之后返回公钥子证书
SecKeyRef publicKeyRef = SecTrustCopyPublicKey(trustRef);
NSAssert(publicKeyRef != NULL, @"公钥创建失败");
if (certificateRef) CFRelease(certificateRef);
if (policyRef) CFRelease(policyRef);
if (trustRef) CFRelease(trustRef);
return publicKeyRef;
}
加载私钥
将.p12 私钥数据获取，并对其存储。
- (SecKeyRef)loadPrivateKey:(NSString *)privateKeyPath password:(NSString *)password {
NSAssert(privateKeyPath.length != 0, @"私钥路径为空");
NSData *PKCS12Data = [NSData dataWithContentsOfFile:privateKeyPath];
CFDataRef inPKCS12Data = (__bridge CFDataRef)PKCS12Data;
CFStringRef passwordRef = (__bridge CFStringRef)password;
// 从 PKCS #12 证书中提取标示和证书
SecIdentityRef myIdentity;
SecTrustRef myTrust;
const void *keys[] = {kSecImportExportPassphrase};
const void *values[] = {passwordRef};
CFDictionaryRef optionsDictionary = CFDictionaryCreate(NULL, keys, values, 1, NULL, NULL);
CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
// 返回 PKCS #12 格式数据中的标示和证书
OSStatus status = SecPKCS12Import(inPKCS12Data, optionsDictionary, &items);
if (status == noErr) {
CFDictionaryRef myIdentityAndTrust = CFArrayGetValueAtIndex(items, 0);
myIdentity = (SecIdentityRef)CFDictionaryGetValue(myIdentityAndTrust, kSecImportItemIdentity);
myTrust = (SecTrustRef)CFDictionaryGetValue(myIdentityAndTrust, kSecImportItemTrust);
}
if (optionsDictionary) CFRelease(optionsDictionary);
NSAssert(status == noErr, @"提取身份和信任失败");
SecTrustResultType trustResult;
// 评估指定证书和策略的信任管理是否有效
status = SecTrustEvaluate(myTrust, &trustResult);
NSAssert(status == errSecSuccess, @"信任评估失败");
SecKeyRef privateKeyRef;
// 提取私钥
status = SecIdentityCopyPrivateKey(myIdentity, &privateKeyRef);
NSAssert(status == errSecSuccess, @"私钥创建失败");
return privateKeyRef;
}
加密数据
- (NSData *)encryptData:(NSData *)plainData {
OSStatus sanityCheck = noErr;
size_t cipherBufferSize = 0;
size_t keyBufferSize = 0;
NSAssert(plainData != nil, @"明文数据为空");
NSAssert(publicKeyRef != nil, @"公钥为空");
NSData *cipher = nil;
uint8_t *cipherBuffer = NULL;
// 计算缓冲区大小
cipherBufferSize = SecKeyGetBlockSize(publicKeyRef);
keyBufferSize = [plainData length];
if (kTypeOfWrapPadding == kSecPaddingNone) {
NSAssert(keyBufferSize <= cipherBufferSize, @"加密内容太大");
} else {
NSAssert(keyBufferSize <= (cipherBufferSize - 11), @"加密内容太大");
}
// 分配缓冲区
cipherBuffer = malloc(cipherBufferSize * sizeof(uint8_t));
memset((void *)cipherBuffer, 0x0, cipherBufferSize);
// 使用公钥加密
sanityCheck = SecKeyEncrypt(publicKeyRef,
kTypeOfWrapPadding,
(const uint8_t *)[plainData bytes],
keyBufferSize,
cipherBuffer,
&cipherBufferSize
);
NSAssert(sanityCheck == noErr, @"加密错误，OSStatus == %d", sanityCheck);
// 生成密文数据
cipher = [NSData dataWithBytes:(const void *)cipherBuffer length:(NSUInteger)cipherBufferSize];
if (cipherBuffer) free(cipherBuffer);
return cipher;
}
解密数据
- (NSData *)decryptData:(NSData *)cipherData {
OSStatus sanityCheck = noErr;
size_t cipherBufferSize = 0;
size_t keyBufferSize = 0;
NSData *key = nil;
uint8_t *keyBuffer = NULL;
SecKeyRef privateKey = NULL;
privateKey = [self getPrivateKeyRef];
NSAssert(privateKey != NULL, @"私钥不存在");
// 计算缓冲区大小
cipherBufferSize = SecKeyGetBlockSize(privateKey);
keyBufferSize = [cipherData length];
NSAssert(keyBufferSize <= cipherBufferSize, @"解密内容太大");
// 分配缓冲区
keyBuffer = malloc(keyBufferSize * sizeof(uint8_t));
memset((void *)keyBuffer, 0x0, keyBufferSize);
// 使用私钥解密
sanityCheck = SecKeyDecrypt(privateKey,
kTypeOfWrapPadding,
(const uint8_t *)[cipherData bytes],
cipherBufferSize,
keyBuffer,
&keyBufferSize
);
NSAssert1(sanityCheck == noErr, @"解密错误，OSStatus == %d", sanityCheck);
// 生成明文数据
key = [NSData dataWithBytes:(const void *)keyBuffer length:(NSUInteger)keyBufferSize];
if (keyBuffer) free(keyBuffer);
return key;
}
通过 openssl 实现 RSA 加解密
首先在工程中 引入 openssl ，openssl 是一个开源库，我们可以使用 OpenSSL-Universal，这个仓库一直在维护，支持 静态库、framework、Cocoapods等等方式引入工程。
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