Promote persistent SMP Key Storage to API: SMPKeyBinv2.2.3

SMPKeyBin stores device's BDAddressAndType, its security connection setup BTSecurityLevel + SMPIOCapability
and optionally the initiator and responder LTK and CSRK within one file.

Since the LTK and CSRK can be optionally set due to their availability per initiator and responder,
implementation supports mixed mode for certain devices,
e.g. LTK responder key only etc.
This was the final motivation to promote the storage demo code to the API.

1 files changed, 393 insertions, 0 deletions

diff --git a/java/org/direct_bt/SMPKeyBin.java b/java/org/direct_bt/SMPKeyBin.java
new file mode 100644
index 00000000..34193db7
--- /dev/null
+++ b/java/org/direct_bt/SMPKeyBin.java
@@ -0,0 +1,393 @@
+/**
+ * Author: Sven Gothel <[email protected]>
+ * Copyright (c) 2021 Gothel Software e.K.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package org.direct_bt;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import org.direct_bt.SMPKeyMask.KeyType;
+
+/**
+ * Storage for a device's {@link BDAddressAndType}, its security connection setup {@link BTSecurityLevel} + {@link SMPIOCapability}
+ * and optionally the initiator and responder {@link SMPLongTermKeyInfo LTK} and {@link SMPSignatureResolvingKeyInfo CSRK} within one file.
+ * <p>
+ * Since the {@link SMPLongTermKeyInfo LTK} and {@link SMPSignatureResolvingKeyInfo CSRK}
+ * can be optionally set due to their availability per initiator and responder,
+ * implementation supports mixed mode for certain devices.
+ * E.g. LTK responder key only etc.
+ * </p>
+ */
+public class SMPKeyBin {
+        public static final short VERSION = (short)0b0101010101010101 + (short)1; // bitpattern + version
+
+        private short version;                          //  2
+        private short  size;                            //  2
+        private final BDAddressAndType addrAndType;     //  7
+        private BTSecurityLevel sec_level;;             //  1
+        private SMPIOCapability io_cap;                 //  1
+
+        private final SMPKeyMask keys_init;             //  1
+        private final SMPKeyMask keys_resp;             //  1
+
+        private SMPLongTermKeyInfo ltk_init;            // 28 (optional)
+        private SMPSignatureResolvingKeyInfo csrk_init; // 17 (optional)
+
+        private SMPLongTermKeyInfo ltk_resp;            // 28 (optional)
+        private SMPSignatureResolvingKeyInfo csrk_resp; // 17 (optional)
+
+        private static final int byte_size_max = 105;
+        private static final int byte_size_min =  15;
+        // Min-Max: 15 - 105 bytes
+
+        boolean verbose;
+
+        final private short calcSize() {
+            short s = 0;
+            s += 2; // sizeof(version);
+            s += 2; // sizeof(size);
+            s += 6; // sizeof(addrAndType.address);
+            s += 1; // sizeof(addrAndType.type);
+            s += 1; // sizeof(sec_level);
+            s += 1; // sizeof(io_cap);
+
+            s += 1; // sizeof(keys_init);
+            s += 1; // sizeof(keys_resp);
+
+            if( hasLTKInit() ) {
+                s += 28; // sizeof(ltk_init);
+            }
+            if( hasCSRKInit() ) {
+                s += 17; // sizeof(csrk_init);
+            }
+
+            if( hasLTKResp() ) {
+                s += 28; // sizeof(ltk_resp);
+            }
+            if( hasCSRKResp() ) {
+                s += 17; // sizeof(csrk_resp);
+            }
+            return s;
+        }
+
+        public SMPKeyBin(final BDAddressAndType addrAndType_,
+                         final BTSecurityLevel sec_level_, final SMPIOCapability io_cap_)
+        {
+            version = VERSION;
+            this.size = 0;
+            this.addrAndType = addrAndType_;
+            this.sec_level = sec_level_;
+            this.io_cap = io_cap_;
+
+            this.keys_init = new SMPKeyMask();
+            this.keys_resp = new SMPKeyMask();
+
+            this.ltk_init = new SMPLongTermKeyInfo();
+            this.csrk_init = new SMPSignatureResolvingKeyInfo();
+
+            this.ltk_resp = new SMPLongTermKeyInfo();
+            this.csrk_resp = new SMPSignatureResolvingKeyInfo();
+
+            this.size = calcSize();
+        }
+
+        public SMPKeyBin() {
+            version = VERSION;
+            size = 0;
+            addrAndType = new BDAddressAndType();
+            sec_level = BTSecurityLevel.UNSET;
+            io_cap = SMPIOCapability.UNSET;
+
+            keys_init = new SMPKeyMask();
+            keys_resp = new SMPKeyMask();
+
+            ltk_init = new SMPLongTermKeyInfo();
+            csrk_init = new SMPSignatureResolvingKeyInfo();
+
+            ltk_resp = new SMPLongTermKeyInfo();
+            csrk_resp = new SMPSignatureResolvingKeyInfo();
+
+            size = calcSize();
+        }
+
+        final public boolean isVersionValid() { return VERSION==version; }
+        final public short getVersion() { return version;}
+
+        final public boolean isSizeValid() { return calcSize() == size;}
+        final public short getSize() { return size;}
+
+        final public BDAddressAndType getAddrAndType() { return addrAndType; }
+        final public BTSecurityLevel getSecLevel() { return sec_level; }
+        final public SMPIOCapability getIOCap() { return io_cap; }
+
+        final public boolean hasLTKInit() { return keys_init.isSet(KeyType.ENC_KEY); }
+        final public boolean hasCSRKInit() { return keys_init.isSet(KeyType.SIGN_KEY); }
+        final public SMPLongTermKeyInfo getLTKInit() { return ltk_init; }
+        final public SMPSignatureResolvingKeyInfo getCSRKInit() { return csrk_init; }
+        final public void setLTKInit(final SMPLongTermKeyInfo v) {
+            ltk_init = v;
+            keys_init.set(KeyType.ENC_KEY);
+            size = calcSize();
+        }
+        final public void setCSRKInit(final SMPSignatureResolvingKeyInfo v) {
+            csrk_init = v;
+            keys_init.set(KeyType.SIGN_KEY);
+            size = calcSize();
+        }
+
+        final public boolean hasLTKResp() { return keys_resp.isSet(KeyType.ENC_KEY); }
+        final public boolean hasCSRKResp() { return keys_resp.isSet(KeyType.SIGN_KEY); }
+        final public SMPLongTermKeyInfo getLTKResp() { return ltk_resp; }
+        final public SMPSignatureResolvingKeyInfo getCSRKResp() { return csrk_resp; }
+        final public void setLTKResp(final SMPLongTermKeyInfo v) {
+            ltk_resp = v;
+            keys_resp.set(KeyType.ENC_KEY);
+            size = calcSize();
+        }
+        final public void setCSRKResp(final SMPSignatureResolvingKeyInfo v) {
+            csrk_resp = v;
+            keys_resp.set(KeyType.SIGN_KEY);
+            size = calcSize();
+        }
+
+        final public void setVerbose(final boolean v) { verbose = v; }
+
+        final public boolean isValid() {
+            return isVersionValid() && isSizeValid() &&
+                   BTSecurityLevel.UNSET != sec_level &&
+                   SMPIOCapability.UNSET != io_cap &&
+                   ( !hasLTKInit() || ltk_init.isValid() ) &&
+                   ( !hasLTKResp() || ltk_resp.isValid() );
+        }
+
+        final public String getFileBasename() {
+            return "bd_"+addrAndType.address.toString()+":"+addrAndType.type.value+".smpkey.bin";
+        }
+        final public static String getFileBasename(final BDAddressAndType addrAndType_) {
+            return "bd_"+addrAndType_.address.toString()+":"+addrAndType_.type.value+".smpkey.bin";
+        }
+
+        @Override
+        final public String toString() {
+            final StringBuilder res = new StringBuilder();
+            res.append("SMPKeyBin[").append(addrAndType.toString()).append(", sec ").append(sec_level).append(", io ").append(io_cap).append(", ");
+            if( isVersionValid() ) {
+                res.append("Init[");
+                if( hasLTKInit() && null != ltk_init ) {
+                    res.append(ltk_init.toString());
+                }
+                if( hasCSRKInit() && null != csrk_init ) {
+                    if( hasLTKInit() ) {
+                        res.append(", ");
+                    }
+                    res.append(csrk_init.toString());
+                }
+                res.append("], Resp[");
+                if( hasLTKResp() && null != ltk_resp ) {
+                    res.append(ltk_resp.toString());
+                }
+                if( hasCSRKResp() && null != csrk_resp ) {
+                    if( hasLTKResp() ) {
+                        res.append(", ");
+                    }
+                    res.append(csrk_resp.toString());
+                }
+                res.append("], ");
+            }
+            res.append("ver[0x").append(Integer.toHexString(version)).append(", ok ").append(isVersionValid()).append("], size[").append(size);
+            if( verbose ) {
+                res.append(", calc ").append(calcSize());
+            }
+            res.append(", valid ").append(isSizeValid()).append("], valid ").append(isValid()).append("]");
+
+            return res.toString();
+        }
+
+        final public boolean write(final String path, final String basename) {
+            if( !isValid() ) {
+                System.err.println("****** WRITE SMPKeyBin: Invalid (skipped) "+toString());
+                return false;
+            }
+            final String fname = path+"/"+basename;
+            final File file = new File(fname);
+            OutputStream out = null;
+            try {
+                file.delete(); // alternative to truncate, if existing
+                out = new FileOutputStream(file);
+                out.write( (byte)  version );
+                out.write( (byte)( version >> 8 ) );
+                out.write( (byte)  size );
+                out.write( (byte)( size >> 8 ) );
+                out.write(addrAndType.address.b);
+                out.write(addrAndType.type.value);
+                out.write(sec_level.value);
+                out.write(io_cap.value);
+
+                out.write(keys_init.mask);
+                out.write(keys_resp.mask);
+
+                if( hasLTKInit() ) {
+                    final byte[] ltk_init_b = new byte[SMPLongTermKeyInfo.byte_size];
+                    ltk_init.getStream(ltk_init_b, 0);
+                    out.write(ltk_init_b);
+                }
+                if( hasCSRKInit() ) {
+                    final byte[] csrk_init_b = new byte[SMPSignatureResolvingKeyInfo.byte_size];
+                    csrk_init.getStream(csrk_init_b, 0);
+                    out.write(csrk_init_b);
+                }
+
+                if( hasLTKResp() ) {
+                    final byte[] ltk_resp_b = new byte[SMPLongTermKeyInfo.byte_size];
+                    ltk_resp.getStream(ltk_resp_b, 0);
+                    out.write(ltk_resp_b);
+                }
+                if( hasCSRKResp() ) {
+                    final byte[] csrk_resp_b = new byte[SMPSignatureResolvingKeyInfo.byte_size];
+                    csrk_resp.getStream(csrk_resp_b, 0);
+                    out.write(csrk_resp_b);
+                }
+                if( verbose ) {
+                    System.err.println("****** WRITE SMPKeyBin: "+fname+": "+toString());
+                }
+                return true;
+            } catch (final Exception ex) {
+                System.err.println("****** WRITE SMPKeyBin: Failed "+fname+": "+toString()+": "+ex.getMessage());
+                ex.printStackTrace();
+            } finally {
+                try {
+                    if( null != out ) {
+                        out.close();
+                    }
+                } catch (final IOException e) {
+                    e.printStackTrace();
+                }
+            }
+            return false;
+        }
+        final public boolean write(final String path) {
+            return write( path, getFileBasename() );
+        }
+
+        final public boolean read(final String path, final String basename) {
+            final String fname = path+"/"+basename;
+            final File file = new File(fname);
+            InputStream in = null;
+            try {
+                if( !file.canRead() ) {
+                    if( verbose ) {
+                        System.err.println("****** READ SMPKeyBin: Failed "+fname+": Not existing or readable: "+toString());
+                    }
+                    return false;
+                }
+                final byte[] buffer = new byte[byte_size_max];
+                in = new FileInputStream(file);
+                read(in, buffer, byte_size_min, fname);
+
+                int i=0;
+                version = (short) ( buffer[i++] | ( buffer[i++] << 8 ) );
+                size = (short) ( buffer[i++] | ( buffer[i++] << 8 ) );
+                addrAndType.address.putStream(buffer, i); i+=6;
+                addrAndType.type = BDAddressType.get(buffer[i++]);
+                sec_level = BTSecurityLevel.get(buffer[i++]);
+                io_cap = SMPIOCapability.get(buffer[i++]);
+
+                keys_init.mask = buffer[i++];
+                keys_resp.mask = buffer[i++];
+
+                int remaining = size - i; // i == byte_size_min == 15
+                boolean err = false;
+
+                if( !err && hasLTKInit() ) {
+                    if( SMPLongTermKeyInfo.byte_size <= remaining ) {
+                        read(in, buffer, SMPLongTermKeyInfo.byte_size, fname);
+                        ltk_init.putStream(buffer, 0);
+                        remaining -= SMPLongTermKeyInfo.byte_size;
+                    } else {
+                        err = true;
+                    }
+                }
+                if( !err && hasCSRKInit() ) {
+                    if( SMPSignatureResolvingKeyInfo.byte_size <= remaining ) {
+                        read(in, buffer, SMPSignatureResolvingKeyInfo.byte_size, fname);
+                        csrk_init.putStream(buffer, 0);
+                        remaining -= SMPSignatureResolvingKeyInfo.byte_size;
+                    } else {
+                        err = true;
+                    }
+                }
+
+                if( !err && hasLTKResp() ) {
+                    if( SMPLongTermKeyInfo.byte_size <= remaining ) {
+                        read(in, buffer, SMPLongTermKeyInfo.byte_size, fname);
+                        ltk_resp.putStream(buffer, 0);
+                        remaining -= SMPLongTermKeyInfo.byte_size;
+                    } else {
+                        err = true;
+                    }
+                }
+                if( !err && hasCSRKResp() ) {
+                    if( SMPSignatureResolvingKeyInfo.byte_size <= remaining ) {
+                        read(in, buffer, SMPSignatureResolvingKeyInfo.byte_size, fname);
+                        csrk_resp.putStream(buffer, 0);
+                        remaining -= SMPSignatureResolvingKeyInfo.byte_size;
+                    } else {
+                        err = true;
+                    }
+                }
+
+                if( verbose ) {
+                    System.err.println("****** READ SMPKeyBin: "+fname+": "+toString()+", remaining "+remaining);
+                }
+                return isValid();
+            } catch (final Exception ex) {
+                System.err.println("****** READ SMPKeyBin: Failed "+fname+": "+toString()+": "+ex.getMessage());
+                ex.printStackTrace();
+            } finally {
+                try {
+                    if( null != in ) {
+                        in.close();
+                    }
+                } catch (final IOException e) {
+                    e.printStackTrace();
+                }
+            }
+            return false;
+        }
+        final public boolean read(final String path, final BDAddressAndType addrAndType_) {
+            return read(path, getFileBasename(addrAndType_));
+        }
+
+        final static private int read(final InputStream in, final byte[] buffer, final int rsize, final String fname) throws IOException {
+            final int read_count = in.read(buffer, 0, rsize);
+            if( read_count != rsize ) {
+                throw new IOException("Couldn't read "+rsize+" bytes, only "+read_count+" from "+fname);
+            }
+            return read_count;
+        }
+};