"key inappropriate for algorithm" error using BouncyCastle

Question

Hi,
I am working on an email client application that sends encrypted emails.
For encryption i have followed the approach :
1) Generated a private/public key pair for RSA using OpenSSL.
2)Generated a certificate using OpenSSL which contains Private and public keys(RSA Keys).
3) Using BouncyCastle to prepare an encrypted MimeMessage instance using SMIMEEnvelopedGenerator like :
SMIMEEnvelopedGenerator gen = new SMIMEEnvelopedGenerator();
gen.addKeyTransRecipient((X509Certificate) chain[0]);
msgbody = gen.generate(msgbody,SMIMEEnvelopedGenerator.RC2_CBC, 2048,"BC");
As the keys contained in the certificate are for RSA and the algorithm specified in the generate() method is "RC2_CBC", it throws an exception
java.io.IOException: org.bouncycastle.cms.CMSException: key inappropriate for algorithm.
     at org.bouncycastle.mail.smime.SMIMEEnvelopedGenerator$ContentEncryptor.write(Unknown Source)
     at org.bouncycastle.mail.smime.handlers.PKCS7ContentHandler.writeTo(Unknown Source)
     at javax.activation.ObjectDataContentHandler.writeTo(DataHandler.java:839)
     at javax.activation.DataHandler.writeTo(DataHandler.java:295)
     at javax.mail.internet.MimeBodyPart.writeTo(MimeBodyPart.java:1209)
     at javax.mail.internet.MimeMessage.writeTo(MimeMessage.java:1614)
     at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:537)
But i tried with all other algo options also and it gives the same error..
Requirement is asymmetric encryption of MimeMessage.
Kindly help me in case someone has faced/solved such a situation or correct me in case the approach is wrong
Thanks

Answer 1

Hi,
I am working on an email client application that sends encrypted emails.
For encryption i have followed the approach :
1) Generated a private/public key pair for RSA using OpenSSL.
2)Generated a certificate using OpenSSL which contains Private and public keys(RSA Keys).
3) Using BouncyCastle to prepare an encrypted MimeMessage instance using SMIMEEnvelopedGenerator like :
SMIMEEnvelopedGenerator gen = new SMIMEEnvelopedGenerator();
gen.addKeyTransRecipient((X509Certificate) chain[0]);
msgbody = gen.generate(msgbody,SMIMEEnvelopedGenerator.RC2_CBC, 2048,"BC");
As the keys contained in the certificate are for RSA and the algorithm specified in the generate() method is "RC2_CBC", it throws an exception
java.io.IOException: org.bouncycastle.cms.CMSException: key inappropriate for algorithm.
     at org.bouncycastle.mail.smime.SMIMEEnvelopedGenerator$ContentEncryptor.write(Unknown Source)
     at org.bouncycastle.mail.smime.handlers.PKCS7ContentHandler.writeTo(Unknown Source)
     at javax.activation.ObjectDataContentHandler.writeTo(DataHandler.java:839)
     at javax.activation.DataHandler.writeTo(DataHandler.java:295)
     at javax.mail.internet.MimeBodyPart.writeTo(MimeBodyPart.java:1209)
     at javax.mail.internet.MimeMessage.writeTo(MimeMessage.java:1614)
     at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:537)
But i tried with all other algo options also and it gives the same error..
Requirement is asymmetric encryption of MimeMessage.
Kindly help me in case someone has faced/solved such a situation or correct me in case the approach is wrong
Thanks