关于RSA加密 后台就给一个公钥

把公钥和你需要编码得Nsstring都转换成NSData
用rsa公钥 编码你所需要编码得内容 最后转换成Nsstring

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//RSA加密 - (NSString *)encryptWithString:(NSString *)content {     NSData *publicKey = [NSData dataFromBase64String:@"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCtkjDEKiKBvg7ps9Cvv1mt2gfnm"];     NSData *usernamm = [content dataUsingEncoding: NSUTF8StringEncoding];     NSData *newKey= [SecKeyWrapper encrypt:usernamm publicKey:publicKey];     NSString *result = [newKey base64EncodedString];     return result; } 还要下载相应 的类 SecKeyWrapper／／／／／／／／／http://www.cocoachina.com/bbs/read.php?tid=232547