Objective-C
You can use (see NSString Class Reference)
- (id)initWithData:(NSData *)data encoding:(NSStringEncoding)encoding
Example:
NSString *myString = [[NSString alloc] initWithData:myData encoding:NSUTF8StringEncoding];
Remark: Please notice the NSData
value must be valid for the encoding specified (UTF-8 in the example above), otherwise nil
will be returned:
Returns nil if the initialization fails for some reason (for example if data does not represent valid data for encoding).
Prior Swift 3.0
String(data: yourData, encoding: NSUTF8StringEncoding)
Swift 3.0 Onwards
String(data: yourData, encoding: .utf8)
See String#init(data:encoding:) Reference
Prior Swift 3.0 :
String(data: yourData, encoding: NSUTF8StringEncoding)
For Swift 4.0:
String(data: yourData, encoding: .utf8)
I believe your "P" as the dataWithBytes param
NSData *keydata = [NSData dataWithBytes:P length:len];
should be "buf"
NSData *keydata = [NSData dataWithBytes:buf length:len];
since i2d_PrivateKey puts the pointer to the output buffer p at the end of the buffer and waiting for further input, and buf is still pointing to the beginning of your buffer.
The following code works for me where pkey is a pointer to an EVP_PKEY:
unsigned char *buf, *pp;
int len = i2d_PrivateKey(pkey, NULL);
buf = OPENSSL_malloc(len);
pp = buf;
i2d_PrivateKey(pkey, &pp);
NSData* pkeyData = [NSData dataWithBytes:(const void *)buf length:len];
DLog(@"Private key in hex (%d): %@", len, pkeyData);
You can use an online converter to convert your binary data into base 64 (http://tomeko.net/online_tools/hex_to_base64.php?lang=en) and compare it to the private key in your cert file after using the following command and checking the output of mypkey.pem:
openssl pkcs12 -in myCert.p12 -nocerts -nodes -out mypkey.pem
I referenced your question and this EVP function site for my answer.
Swift 3:
String(data: data, encoding: .utf8)
Swift 5:
String(data: data!, encoding: String.Encoding.utf8)
A simple way to convert arbitrary NSData to NSString is to base64 encode it.
NSString *base64EncodedKey = [keydata base64EncodedStringWithOptions: NSDataBase64Encoding64CharacterLineLength];
You can then store it into your database for reuse later. Just decode it back to NSData.
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