Update documentation

xed25519.cpp

@@ -20,6 +20,12 @@ x25519::x25519(const byte y[32], const byte x[32])
     std::memcpy(m_sk, x, 32);
 }
 
+x25519::x25519(const byte x[32])
+{
+    std::memcpy(m_sk, x, 32);
+    GeneratePublicKey(NullRNG(), m_sk, m_pk);
+}
+
 x25519::x25519(const Integer &y, const Integer &x)
 {
     ArraySink ys(m_pk, 32);
@@ -29,6 +35,13 @@ x25519::x25519(const Integer &y, const Integer &x)
     x.Encode(xs, 32);
 }
 
+x25519::x25519(const Integer &x)
+{
+    ArraySink xs(m_sk, 32);
+    x.Encode(xs, 32);
+    GeneratePublicKey(NullRNG(), m_sk, m_pk);
+}
+
 x25519::x25519(RandomNumberGenerator &rng)
 {
     GeneratePrivateKey(rng, m_sk);

xed25519.h

@@ -2,31 +2,76 @@
 //              Crypto++ specific implementation wrapped around Adam
 //              Langley's curve25519-donna.
 
+// Typically the key agreement classes encapsulate their data more
+// than x25519 does below. We made them a little more accessible
+// due to crypto_box operations. Once the library cuts-in the
+// crypto_box operations the x25519 class will be more restricted.
+
 #ifndef CRYPTOPP_XED25519_H
 #define CRYPTOPP_XED25519_H
 
 #include "cryptlib.h"
-#include "algparam.h"
 
 NAMESPACE_BEGIN(CryptoPP)
 
 class Integer;
 
 /// \brief x25519 with key validation
+/// \since Crypto++ 8.0
 class x25519 : public SimpleKeyAgreementDomain, public CryptoParameters
 {
 public:
+    /// \brief Create a x25519 object
+    /// \param y public key
+    /// \param x private key
+    /// \details This constructor creates a x25519 object using existing parameters.
+    /// \note The public key is not validated.
     x25519(const byte y[32], const byte x[32]);
+
+    /// \brief Create a x25519 object
+    /// \param x private key
+    /// \details This constructor creates a x25519 object using existing parameters.
+    ///   The public key is calculated from the private key.
+    x25519(const byte x[32]);
+
+    /// \brief Create a x25519 object
+    /// \param y public key
+    /// \param x private key
+    /// \details This constructor creates a x25519 object using existing parameters.
+    /// \note The public key is not validated.
     x25519(const Integer &y, const Integer &x);
+
+    /// \brief Create a x25519 object
+    /// \param x private key
+    /// \details This constructor creates a x25519 object using existing parameters.
+    ///   The public key is calculated from the private key.
+    x25519(const Integer &x);
+
+    /// \brief Create a x25519 object
+    /// \param rng RandomNumberGenerator derived class
+    /// \details This constructor creates a new x25519 using the random number generator.
     x25519(RandomNumberGenerator &rng);
+
+    /// \brief Create a x25519 object
+    /// \param params public and private key
+    /// \param y private key
+    /// \details This constructor creates a x25519 object using existing parameters.
+    ///   The <tt>params</tt> can be created with <tt>DEREncode</tt>.
+    /// \note The public key is not validated.
     x25519(BufferedTransformation &params);
 
+    /// \brief Decode a x25519 object
+    /// \param params serialized object
+    /// \details DEREncode() writes the public and private key as an ASN.1 structure.
+    ///   The private key is written first as a <tt>BIT_STRING</tt>. The public key
+    ///   is written second as an <tt>OCTET_STRING</tt>.
     void DEREncode(BufferedTransformation &params) const;
 
     bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
     bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
     void AssignFrom(const NameValuePairs &source);
     CryptoParameters & AccessCryptoParameters() {return *this;}
+
     unsigned int AgreedValueLength() const {return 32;}
     unsigned int PrivateKeyLength() const {return 32;}
     unsigned int PublicKeyLength() const {return 32;}