private static Assertion decryptAssertion(EncryptedAssertion encryptedAssertion,
                                              Credential decryptionCredential) {
        final StaticKeyInfoCredentialResolver keyInfoCredentialResolver =
                new StaticKeyInfoCredentialResolver(decryptionCredential);
        final Decrypter decrypter =
                new Decrypter(null, keyInfoCredentialResolver, new InlineEncryptedKeyResolver());
        decrypter.setRootInNewDocument(true);
        try {
            return decrypter.decrypt(encryptedAssertion);
        } catch (DecryptionException e) {
            throw new InvalidSamlRequestException("failed to decrypt an assertion", e);
        }
    }
A service which receives an assertion from the remote identity provider.
saml/src/main/java/com/linecorp/armeria/server/saml/SamlAssertionConsumerFunction.java