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Java decrypt email attachment (.p7m file)

I have an email attachment in .p7m format and a .pem file containing private keys and certificates.
Using OpenSSL I can decrypt the file with this command:
openssl smime -decrypt -inform DER -in fileToDecrypt.p7m -inkey privateKey.pem -out destinationFile
But using bouncycastle in Java, I could not decrypt it.
I read the private key with this code:
PEMReader pemReader = new PEMReader(new InputStreamReader(new FileInputStream(privateKeyName)));
Object obj;
PrivateKey key = null;
X509Certificate cert1 = null;
X509Certificate cert2 = null;
obj = pemReader.readObject();
if (obj instanceof PrivateKey) {
key = (PrivateKey) obj;
System.out.println("Private Key found");
}
obj = pemReader.readObject();
if(obj instanceof X509Certificate){
cert1 = (X509Certificate) obj;
System.out.println("cert found");
}
obj = pemReader.readObject();
if(obj instanceof X509Certificate){
cert2 = (X509Certificate) obj;
System.out.println("cert found");
}
This prints out:
Private Key Found
cert found
cert found
The type of the keys are:
System.out.println(key.getAlgorithm());
System.out.println(cert1.getSigAlgName());
System.out.println(cert2.getSigAlgName());
RSA
SHA256WithRSAEncryption
SHA256WithRSAEncryption
If I try to decrypt like this:
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, key);
Path path = Paths.get("fileToDecrypt.p7m");
byte[] data = Files.readAllBytes(path);
byte[] decryptedData = cipher.doFinal(data);
I get:
javax.crypto.IllegalBlockSizeException: Data must not be longer than 256 bytes
I have this two files:
fileToDecrypt.p7m
privateKey.pem: containing RSA private key and two X508 Certificates
And I don't know where to begin what to decrypt with what, and how?

Solution to the problem:
private static byte[] cmsDecrypt(byte[] message, PrivateKey key) throws
Exception {
CMSEnvelopedDataParser ep = new CMSEnvelopedDataParser(message);
RecipientInformationStore recipients = ep.getRecipientInfos();
Collection c = recipients.getRecipients();
Iterator iter = c.iterator();
RecipientInformation recipient = (RecipientInformation) iter.next();
return recipient.getContent(key, new BouncyCastleProvider());
}
Path path = Paths.get("fileToDecrypt.p7m");
byte[] data = Files.readAllBytes(path);
try {
System.out.println(new String(cmsDecrypt(data, key)));
} catch (Exception e) {
e.printStackTrace();
}

Encrypt private key with java code

i have generate a private key with java code and a save it so:
KeyPair keys;
try {
keys = KeyTools.genKeys("2048", AlgorithmConstants.KEYALGORITHM_RSA);
//SAVE PRIVKEY
//PrivateKey privKey = keys.getPrivate();
//byte[] privateKeyBytes = privKey.getEncoded();
PKCS10CertificationRequest pkcs10 = new PKCS10CertificationRequest("SHA256WithRSA",
CertTools.stringToBcX509Name("CN=NOUSED"), keys.getPublic(), null, keys.getPrivate());
//Save Privatekey
String privateKeyFilename = "C:/Users/l.calicchio/Downloads/privateKey.key";
String password="prismaPrivateKey";
byte[] start="-----BEGIN PRIVATE KEY-----\n".getBytes();
byte[] end="\n-----END PRIVATE KEY-----".getBytes();
byte[] privateKeyBytes = keys.getPrivate().getEncoded();
byte[] encryptedPrivateKeyBytes = passwordEncrypt(password.toCharArray(), privateKeyBytes);
File f=new File(privateKeyFilename);
if (f.exists()){
f.delete();
}
FileOutputStream fos = new FileOutputStream(f,true);
fos.write(start);
fos.write(Base64.encode(encryptedPrivateKeyBytes));
fos.write(end);
fos.close();
Now i want add passphrase to private key.
so i found this code:
private static byte[] passwordEncrypt(char[] password, byte[] plaintext) throws Exception {
String MYPBEALG = "PBEWithSHA1AndDESede";
int count = 20;// hash iteration count
SecureRandom random = new SecureRandom();
byte[] salt = new byte[8];
random.nextBytes(salt);
// Create PBE parameter set
PBEParameterSpec pbeParamSpec = new PBEParameterSpec(salt, count);
PBEKeySpec pbeKeySpec = new PBEKeySpec(password);
SecretKeyFactory keyFac = SecretKeyFactory.getInstance(MYPBEALG);
SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec);
Cipher pbeCipher = Cipher.getInstance(MYPBEALG);
// Initialize PBE Cipher with key and parameters
pbeCipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec);
// Encrypt the encoded Private Key with the PBE key
byte[] ciphertext = pbeCipher.doFinal(plaintext);
// Now construct PKCS #8 EncryptedPrivateKeyInfo object
AlgorithmParameters algparms = AlgorithmParameters.getInstance(MYPBEALG);
algparms.init(pbeParamSpec);
EncryptedPrivateKeyInfo encinfo = new EncryptedPrivateKeyInfo(algparms, ciphertext);
// and here we have it! a DER encoded PKCS#8 encrypted key!
return encinfo.getEncoded();
but when i use this openssl command
openssl asn1parse -in privateKey.key
i have no error, but when i try this:
openssl rsa -noout -modulus -in privatekey.it
i have a error:
unable to load private key 9964:error:0D0680A8:asn1 encoding
routines:ASN1_CHECK_TLEN:wrong tag:.\crypto\as n1\tasn_dec.c:1319:
9964:error:0D06C03A:asn1 encoding
routines:ASN1_D2I_EX_PRIMITIVE:nested asn1 err
or:.\crypto\asn1\tasn_dec.c:831: 9964:error:0D08303A:asn1 encoding
routines:ASN1_TEMPLATE_NOEXP_D2I:nested asn1 e
rror:.\crypto\asn1\tasn_dec.c:751:Field=version,
Type=PKCS8_PRIV_KEY_INFO 9964:error:0907B00D:PEM
routines:PEM_READ_BIO_PRIVATEKEY:ASN1 lib:.\crypto\pem\p
em_pkey.c:132:
I think that the private key is missing the following line:
Proc-Type: 4,ENCRYPTED
"DEK-Info: " + "AES-256-CBC"......
but how i add this(where i get this information?)?
tnx

Please read the manual, man rsa gives the following details:
Note this command uses
the traditional SSLeay compatible format for private key encryption:
newer applications should use the more secure PKCS#8 format using the
pkcs8 utility.

Unable to load RSA public key

I'm trying to read RSA public key shown below, but I get an exception at line 6: java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException: algid parse error, not a sequence
My code:
String rsaPublicKey = rsaPublicKeyString.replace(
"-----BEGIN RSA PUBLIC KEY-----\n", "");
rsaPublicKey = rsaPublicKey.replace("\n-----END RSA PUBLIC KEY-----", "");
byte[] bytes = EncryptionUtils.decodeBase64(rsaPublicKey);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes);
pubKey = (RSAPublicKey)keyFactory.generatePublic(keySpec);
RSA public key:
-----BEGIN RSA PUBLIC KEY-----
MIIBCgKCAQEAwVACPi9w23mF3tBkdZz+zwrzKOaaQdr01vAbU4E1pvkfj4sqDsm6
lyDONS789sVoD/xCS9Y0hkkC3gtL1tSfTlgCMOOul9lcixlEKzwKENj1Yz/s7daS
an9tqw3bfUV/nqgbhGX81v/+7RFAEd+RwFnK7a+XYl9sluzHRyVVaTTveB2GazTw
Efzk2DWgkBluml8OREmvfraX3bkHZJTKX4EQSjBbbdJ2ZXIsRrYOXfaA+xayEGB+
8hdlLmAjbCVfaigxX0CDqWeR1yFL9kwd9P0NsZRPsmoqVwMbMu7mStFai6aIhc3n
Slv8kg9qv1m6XHVQY3PnEw+QQtqSIXklHwIDAQAB
-----END RSA PUBLIC KEY-----
What am I doing wrong?
UPD:
public static byte[] decodeBase64(String data) throws EncryptionException {
try {
BASE64Decoder decoder = new BASE64Decoder();
return decoder.decodeBuffer(data);
} catch (Exception e) {
throw new EncryptionException(e);
}
}

For me, I was missing the OID in the public key. I had to correct that on the iOS side using help from here: http://blog.wingsofhermes.org/?p=42
Also, my public key didn't have to be casted to an RSAPublicKey, the standard worked just fine:
X509EncodedKeySpec pubKeySpec = new X509EncodedKeySpec(publicKeyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
PublicKey pubKey = keyFactory.generatePublic(pubKeySpec);

Your problem is caused because your public key is an RSAPublicKey object rather than a SubjectPublicKeyInfo object (see this answer for a good description of the difference). You will need to convert from one to the other before your code will work.
BouncyCastle can do the conversion for you. The following code snippet will work, although I dislike it for two reasons:
It uses a deprecated class PEMReader.
It requires the BouncyCastle provider to be loaded.
Code:
Security.addProvider(new BouncyCastleProvider());
PEMReader reader = new PEMReader(new StringReader(rsaPublicKeyString));
BCRSAPublicKey key = (BCRSAPublicKey) reader.readObject();
bytes[] = key.getEncoded(); // now in SubjectPublicKeyInfo format.
// as before...
With BouncyCastle, there is always many ways to skin a cat. Perhaps someone can find a more elegant solution than the one above?

javax.crypto.BadPaddingException: Data must start with zero

First of all, this is not a duplicate question. I am facing a very strange issue.
Following is what I do.
Case 1:
Generate Key Pair
Encrypt Using Private Key
Decrypt Using Public Key
Everything works fine.
Case 2:
Load Certificate from Mozila Firefox Key Store
Use Certificate A
Encrypt Using Private Key of Certificate A
Decrypt Using Public Keu of Certificate A
Everything works fine.
Case 3:
Load Certificate from Internet Explorer Key Store
Use Certificate A
Encrypt Using Private Key of Certificate A
Decrypt Using Public Keu of Certificate A
At Decrypt time, I get error of BadPadding exception
Following is snippet of each of my codes.
Generating Key Pair
KeyPair keyPair = KeyPairGenerator.getInstance("RSA").generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();
Load Mozilla KeyStore
String strCfg = System.getProperty("user.home")+ File.separator + "jdk6-nss-mozilla.cfg";
Provider p1 = new sun.security.pkcs11.SunPKCS11(strCfg);
Security.addProvider(p1);
keyStore = KeyStore.getInstance("PKCS11");
keyStore.load(null, "password".toCharArray());
Content of Config file
name=NSS
slot=2
library=C:/Program Files/Mozilla Firefox/softokn3.dll
nssArgs="configDir='C:/Documents and Settings/pratik.vohera.DIGI-CORP/Application Data/Mozilla/Firefox/Profiles/t48xsipj.default' certPrefix='' keyPrefix='' secmod='secmod.db' flags=readOnly"
Load IE KeyStore
keyStore = KeyStore.getInstance("Windows-MY");
keyStore.load(null, null);
Get Public and Private key from KeyStore
if (keyStore != null) {
Enumeration<String> enumaration = null;
try {
enumaration = keyStore.aliases();
} catch (KeyStoreException e1) {
e1.printStackTrace();
}
ArrayList<String> certiList;
while (enumaration.hasMoreElements()) {
String aliases = enumaration.nextElement();
certiList = new ArrayList<String>();
certiList.add(aliases);
try {
selectedCert = keyStore.getCertificate(aliases);
selectedpublickey = (RSAPublicKey) selectedCert.getPublicKey();
selectedAlias = aliases;
selectedprivateKey = (PrivateKey) keyStore.getKey(selectedAlias, null);}
} catch (KeyStoreException e) {
e.printStackTrace();
}
}
Encryption
private static String publicEncrypt(String text, Key pubKey) throws Exception {
BASE64Encoder bASE64Encoder = new BASE64Encoder();
byte[] plainText = text.getBytes();
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
String encryptedText = bASE64Encoder.encode(cipher.doFinal(plainText));
return encryptedText;
}
Decryption
private static String privateDecrypt(String text, Key priKey)throws Exception {
BASE64Decoder base64Decoder = new BASE64Decoder();
byte[] encryptText = base64Decoder.decodeBuffer(text);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, priKey);
String decryptedString = new String(cipher.doFinal(encryptText));
return decryptedString;
}
Exception Stacktrace
javax.crypto.BadPaddingException: Data must start with zero
at sun.security.rsa.RSAPadding.unpadV15(Unknown Source)
at sun.security.rsa.RSAPadding.unpad(Unknown Source)
at com.sun.crypto.provider.RSACipher.a(DashoA13*..)
at com.sun.crypto.provider.RSACipher.engineDoFinal(DashoA13*..)
at javax.crypto.Cipher.doFinal(DashoA13*..)
at test.testclass.privateDecrypt(testclass.java:198)
at test.testclass.test(testclass.java:137)
at test.testclass.main(testclass.java:120)
I have been working on this for a long time. This is very important. Do let me know if any further information is required.

In the third case, the problem is: You try to encrypt using the private key and decrypt using the public key which is wrong. You should always decrypt using the private key.

RSA encryption :InvalidKeyException: invalid key format

I have to read pem key files to get RSA Public key,and then use them to encrypt.
I can do this using openssl and convert pem file to der file.
and then load my key using X509EncodedKeySpec and PKCS8EncodedKeySpec.
But I don't want to do this because pem is the user key exchange format.
user can register it's own key can like this :
--BEGIN PUBLIC KEY-- MIGeMA0GCSqGSIb3DQEBAQUAA4GMADCBiAKBgGi0/vKrSIIQMOm4atiw+2s8tSojOKHsWJU3oPTm
b1a5UQIH7CM3NgtLvUF5DqhsP2jTqgYSsZSl+W2RtqCFTavZTWvmc0UsuK8tTzvnCXETsnpjeL13
Hul9JIpxZVej7b6KxgyxFAhuz2AGscvCXnepElkVh7oGOqkUKL7gZSD7AgMBAAE=
--END PUBLIC KEY--
and this key is store in a database in this format...
Here is the code I have tried..
File pubKeyFile=new File("D:/public_key.pem");
DataInputStream dis = new DataInputStream(new FileInputStream(pubKeyFile));
byte[] pubKeyBytes = new byte[(int)pubKeyFile.length()];
dis.readFully(pubKeyBytes);
dis.close();
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec pubSpec = new X509EncodedKeySpec(pubKeyBytes);
RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubSpec);
I am getting exception as
java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: invalid key format
As I am completely new to encryption concepts can anyone please help me to solve this exception?
Many thanks.

With bouncycastle, it would be done this way:
CertificateFactory cf = CertificateFactory.getInstance("X509", "BC");
InputStream is = new FileInputStream("D:/public_key.pem");
X509Certificate certificate = (X509Certificate) cf.generateCertificate(is);
is.close();
RSAPublicKey pubKey = (RSAPublicKey)certificate.getPublicKey();

You were almost there, with the standard provider. You just need to strip the header and footer lines:
List<String> lines = Files.readAllLines(Paths.get(path), StandardCharsets.US_ASCII);
if (lines.size() < 2)
throw new IllegalArgumentException("Insufficient input");
if (!lines.remove(0).startsWith("--"))
throw new IllegalArgumentException("Expected header");
if (!lines.remove(lines.size() - 1).startsWith("--"))
throw new IllegalArgumentException("Expected footer");
byte[] raw = Base64.getDecoder().decode(String.join("", lines));
KeyFactory factory = KeyFactory.getInstance("RSA");
PublicKey pub = factory.generatePublic(new X509EncodedKeySpec(raw));

try using bouncycastele's PemReader .
PublicKey getPublicKey(String pubKeyStr) throws IOException, NoSuchAlgorithmException, InvalidKeySpecException {
PemObject pem = new PemReader(new StringReader(pubKeyStr)).readPemObject();
byte[] pubKeyBytes = pem.getContent();
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
X509EncodedKeySpec pubSpec = new X509EncodedKeySpec(pubKeyBytes);
RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubSpec);
return pubKey;
}