1 files changed, 410 insertions, 0 deletions
diff --git a/src/lib/asn1/der_enc.cpp b/src/lib/asn1/der_enc.cpp
new file mode 100644
index 000000000..c1e5fd45c
--- /dev/null
+++ b/src/lib/asn1/der_enc.cpp
@@ -0,0 +1,410 @@
+/*
+* DER Encoder
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/der_enc.h>
+#include <botan/asn1_obj.h>
+#include <botan/bigint.h>
+#include <botan/get_byte.h>
+#include <botan/parsing.h>
+#include <botan/internal/bit_ops.h>
+#include <algorithm>
+
+namespace Botan {
+
+namespace {
+
+/*
+* DER encode an ASN.1 type tag
+*/
+secure_vector<byte> encode_tag(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if((class_tag | 0xE0) != 0xE0)
+      throw Encoding_Error("DER_Encoder: Invalid class tag " +
+                           std::to_string(class_tag));
+
+   secure_vector<byte> encoded_tag;
+   if(type_tag <= 30)
+      encoded_tag.push_back(static_cast<byte>(type_tag | class_tag));
+   else
+      {
+      size_t blocks = high_bit(type_tag) + 6;
+      blocks = (blocks - (blocks % 7)) / 7;
+
+      encoded_tag.push_back(class_tag | 0x1F);
+      for(size_t i = 0; i != blocks - 1; ++i)
+         encoded_tag.push_back(0x80 | ((type_tag >> 7*(blocks-i-1)) & 0x7F));
+      encoded_tag.push_back(type_tag & 0x7F);
+      }
+
+   return encoded_tag;
+   }
+
+/*
+* DER encode an ASN.1 length field
+*/
+secure_vector<byte> encode_length(size_t length)
+   {
+   secure_vector<byte> encoded_length;
+   if(length <= 127)
+      encoded_length.push_back(static_cast<byte>(length));
+   else
+      {
+      const size_t top_byte = significant_bytes(length);
+
+      encoded_length.push_back(static_cast<byte>(0x80 | top_byte));
+
+      for(size_t i = sizeof(length) - top_byte; i != sizeof(length); ++i)
+         encoded_length.push_back(get_byte(i, length));
+      }
+   return encoded_length;
+   }
+
+}
+
+/*
+* Return the encoded SEQUENCE/SET
+*/
+secure_vector<byte> DER_Encoder::DER_Sequence::get_contents()
+   {
+   const ASN1_Tag real_class_tag = ASN1_Tag(class_tag | CONSTRUCTED);
+
+   if(type_tag == SET)
+      {
+      std::sort(set_contents.begin(), set_contents.end());
+      for(size_t i = 0; i != set_contents.size(); ++i)
+         contents += set_contents[i];
+      set_contents.clear();
+      }
+
+   secure_vector<byte> result;
+   result += encode_tag(type_tag, real_class_tag);
+   result += encode_length(contents.size());
+   result += contents;
+   contents.clear();
+
+   return result;
+   }
+
+/*
+* Add an encoded value to the SEQUENCE/SET
+*/
+void DER_Encoder::DER_Sequence::add_bytes(const byte data[], size_t length)
+   {
+   if(type_tag == SET)
+      set_contents.push_back(secure_vector<byte>(data, data + length));
+   else
+      contents += std::make_pair(data, length);
+   }
+
+/*
+* Return the type and class taggings
+*/
+ASN1_Tag DER_Encoder::DER_Sequence::tag_of() const
+   {
+   return ASN1_Tag(type_tag | class_tag);
+   }
+
+/*
+* DER_Sequence Constructor
+*/
+DER_Encoder::DER_Sequence::DER_Sequence(ASN1_Tag t1, ASN1_Tag t2) :
+   type_tag(t1), class_tag(t2)
+   {
+   }
+
+/*
+* Return the encoded contents
+*/
+secure_vector<byte> DER_Encoder::get_contents()
+   {
+   if(subsequences.size() != 0)
+      throw Invalid_State("DER_Encoder: Sequence hasn't been marked done");
+
+   secure_vector<byte> output;
+   std::swap(output, contents);
+   return output;
+   }
+
+/*
+* Start a new ASN.1 SEQUENCE/SET/EXPLICIT
+*/
+DER_Encoder& DER_Encoder::start_cons(ASN1_Tag type_tag,
+                                     ASN1_Tag class_tag)
+   {
+   subsequences.push_back(DER_Sequence(type_tag, class_tag));
+   return (*this);
+   }
+
+/*
+* Finish the current ASN.1 SEQUENCE/SET/EXPLICIT
+*/
+DER_Encoder& DER_Encoder::end_cons()
+   {
+   if(subsequences.empty())
+      throw Invalid_State("DER_Encoder::end_cons: No such sequence");
+
+   secure_vector<byte> seq = subsequences[subsequences.size()-1].get_contents();
+   subsequences.pop_back();
+   raw_bytes(seq);
+   return (*this);
+   }
+
+/*
+* Start a new ASN.1 EXPLICIT encoding
+*/
+DER_Encoder& DER_Encoder::start_explicit(u16bit type_no)
+   {
+   ASN1_Tag type_tag = static_cast<ASN1_Tag>(type_no);
+
+   if(type_tag == SET)
+      throw Internal_Error("DER_Encoder.start_explicit(SET); cannot perform");
+
+   return start_cons(type_tag, CONTEXT_SPECIFIC);
+   }
+
+/*
+* Finish the current ASN.1 EXPLICIT encoding
+*/
+DER_Encoder& DER_Encoder::end_explicit()
+   {
+   return end_cons();
+   }
+
+/*
+* Write raw bytes into the stream
+*/
+DER_Encoder& DER_Encoder::raw_bytes(const secure_vector<byte>& val)
+   {
+   return raw_bytes(&val[0], val.size());
+   }
+
+DER_Encoder& DER_Encoder::raw_bytes(const std::vector<byte>& val)
+   {
+   return raw_bytes(&val[0], val.size());
+   }
+
+/*
+* Write raw bytes into the stream
+*/
+DER_Encoder& DER_Encoder::raw_bytes(const byte bytes[], size_t length)
+   {
+   if(subsequences.size())
+      subsequences[subsequences.size()-1].add_bytes(bytes, length);
+   else
+      contents += std::make_pair(bytes, length);
+
+   return (*this);
+   }
+
+/*
+* Encode a NULL object
+*/
+DER_Encoder& DER_Encoder::encode_null()
+   {
+   return add_object(NULL_TAG, UNIVERSAL, nullptr, 0);
+   }
+
+/*
+* DER encode a BOOLEAN
+*/
+DER_Encoder& DER_Encoder::encode(bool is_true)
+   {
+   return encode(is_true, BOOLEAN, UNIVERSAL);
+   }
+
+/*
+* DER encode a small INTEGER
+*/
+DER_Encoder& DER_Encoder::encode(size_t n)
+   {
+   return encode(BigInt(n), INTEGER, UNIVERSAL);
+   }
+
+/*
+* DER encode a small INTEGER
+*/
+DER_Encoder& DER_Encoder::encode(const BigInt& n)
+   {
+   return encode(n, INTEGER, UNIVERSAL);
+   }
+
+/*
+* DER encode an OCTET STRING or BIT STRING
+*/
+DER_Encoder& DER_Encoder::encode(const secure_vector<byte>& bytes,
+                                 ASN1_Tag real_type)
+   {
+   return encode(&bytes[0], bytes.size(),
+                 real_type, real_type, UNIVERSAL);
+   }
+
+/*
+* DER encode an OCTET STRING or BIT STRING
+*/
+DER_Encoder& DER_Encoder::encode(const std::vector<byte>& bytes,
+                                 ASN1_Tag real_type)
+   {
+   return encode(&bytes[0], bytes.size(),
+                 real_type, real_type, UNIVERSAL);
+   }
+
+/*
+* Encode this object
+*/
+DER_Encoder& DER_Encoder::encode(const byte bytes[], size_t length,
+                                 ASN1_Tag real_type)
+   {
+   return encode(bytes, length, real_type, real_type, UNIVERSAL);
+   }
+
+/*
+* DER encode a BOOLEAN
+*/
+DER_Encoder& DER_Encoder::encode(bool is_true,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   byte val = is_true ? 0xFF : 0x00;
+   return add_object(type_tag, class_tag, &val, 1);
+   }
+
+/*
+* DER encode a small INTEGER
+*/
+DER_Encoder& DER_Encoder::encode(size_t n,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return encode(BigInt(n), type_tag, class_tag);
+   }
+
+/*
+* DER encode an INTEGER
+*/
+DER_Encoder& DER_Encoder::encode(const BigInt& n,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if(n == 0)
+      return add_object(type_tag, class_tag, 0);
+
+   bool extra_zero = (n.bits() % 8 == 0);
+   secure_vector<byte> contents(extra_zero + n.bytes());
+   BigInt::encode(&contents[extra_zero], n);
+   if(n < 0)
+      {
+      for(size_t i = 0; i != contents.size(); ++i)
+         contents[i] = ~contents[i];
+      for(size_t i = contents.size(); i > 0; --i)
+         if(++contents[i-1])
+            break;
+      }
+
+   return add_object(type_tag, class_tag, contents);
+   }
+
+/*
+* DER encode an OCTET STRING or BIT STRING
+*/
+DER_Encoder& DER_Encoder::encode(const secure_vector<byte>& bytes,
+                                 ASN1_Tag real_type,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return encode(&bytes[0], bytes.size(),
+                 real_type, type_tag, class_tag);
+   }
+
+/*
+* DER encode an OCTET STRING or BIT STRING
+*/
+DER_Encoder& DER_Encoder::encode(const std::vector<byte>& bytes,
+                                 ASN1_Tag real_type,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return encode(&bytes[0], bytes.size(),
+                 real_type, type_tag, class_tag);
+   }
+
+/*
+* DER encode an OCTET STRING or BIT STRING
+*/
+DER_Encoder& DER_Encoder::encode(const byte bytes[], size_t length,
+                                 ASN1_Tag real_type,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if(real_type != OCTET_STRING && real_type != BIT_STRING)
+      throw Invalid_Argument("DER_Encoder: Invalid tag for byte/bit string");
+
+   if(real_type == BIT_STRING)
+      {
+      secure_vector<byte> encoded;
+      encoded.push_back(0);
+      encoded += std::make_pair(bytes, length);
+      return add_object(type_tag, class_tag, encoded);
+      }
+   else
+      return add_object(type_tag, class_tag, bytes, length);
+   }
+
+/*
+* Conditionally write some values to the stream
+*/
+DER_Encoder& DER_Encoder::encode_if(bool cond, DER_Encoder& codec)
+   {
+   if(cond)
+      return raw_bytes(codec.get_contents());
+   return (*this);
+   }
+
+DER_Encoder& DER_Encoder::encode_if(bool cond, const ASN1_Object& obj)
+   {
+   if(cond)
+      encode(obj);
+   return (*this);
+   }
+
+/*
+* Request for an object to encode itself
+*/
+DER_Encoder& DER_Encoder::encode(const ASN1_Object& obj)
+   {
+   obj.encode_into(*this);
+   return (*this);
+   }
+
+/*
+* Write the encoding of the byte(s)
+*/
+DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
+                                     const byte rep[], size_t length)
+   {
+   secure_vector<byte> buffer;
+   buffer += encode_tag(type_tag, class_tag);
+   buffer += encode_length(length);
+   buffer += std::make_pair(rep, length);
+
+   return raw_bytes(buffer);
+   }
+
+/*
+* Write the encoding of the byte(s)
+*/
+DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
+                                     const std::string& rep_str)
+   {
+   const byte* rep = reinterpret_cast<const byte*>(rep_str.data());
+   const size_t rep_len = rep_str.size();
+   return add_object(type_tag, class_tag, rep, rep_len);
+   }
+
+/*
+* Write the encoding of the byte
+*/
+DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag,
+                                     ASN1_Tag class_tag, byte rep)
+   {
+   return add_object(type_tag, class_tag, &rep, 1);
+   }
+
+}