CERT

Apple's certificates on IMG2, IMG3, and IMG4 files. Some hardware tags like CHIP and PROD are actually within this section and technically not in the signature checked area, but that does not matter as in parseCertificatesAndSignature; in iBoot, they are compared against a hardcoded value for whatever they should be set to.

Parsed
0:d=0 hl=4 l=1211 cons: SEQUENCE 4:d=1 hl=4 l= 931 cons: SEQUENCE 8:d=2 hl=2 l=   3 cons: cont [ 0 ] 10:d=3 hl=2 l=   1 prim: INTEGER           :02 13:d=2 hl=2 l=   1 prim: INTEGER           :02 16:d=2 hl=2 l=  13 cons: SEQUENCE 18:d=3 hl=2 l=   9 prim: OBJECT            :sha1WithRSAEncryption 29:d=3 hl=2 l=   0 prim: NULL 31:d=2 hl=2 l=  98 cons: SEQUENCE 33:d=3 hl=2 l=  11 cons: SET 35:d=4 hl=2 l=   9 cons: SEQUENCE 37:d=5 hl=2 l=   3 prim: OBJECT            :countryName 42:d=5 hl=2 l=   2 prim: PRINTABLESTRING   :US 46:d=3 hl=2 l=  19 cons: SET 48:d=4 hl=2 l=  17 cons: SEQUENCE 50:d=5 hl=2 l=   3 prim: OBJECT            :organizationName 55:d=5 hl=2 l=  10 prim: PRINTABLESTRING   :Apple Inc.   67:d=3  hl=2 l=  38 cons: SET 69:d=4 hl=2 l=  36 cons: SEQUENCE 71:d=5 hl=2 l=   3 prim: OBJECT            :organizationalUnitName 76:d=5 hl=2 l=  29 prim: PRINTABLESTRING   :Apple Certification Authority 107:d=3 hl=2 l=  22 cons: SET 109:d=4 hl=2 l=  20 cons: SEQUENCE 111:d=5 hl=2 l=   3 prim: OBJECT            :commonName 116:d=5 hl=2 l=  13 prim: PRINTABLESTRING   :Apple Root CA  131:d=2  hl=2 l=  30 cons: SEQUENCE 133:d=3 hl=2 l=  13 prim: UTCTIME           :060425214036Z 148:d=3 hl=2 l=  13 prim: UTCTIME           :350209214036Z 163:d=2 hl=2 l=  98 cons: SEQUENCE 165:d=3 hl=2 l=  11 cons: SET 167:d=4 hl=2 l=   9 cons: SEQUENCE 169:d=5 hl=2 l=   3 prim: OBJECT            :countryName 174:d=5 hl=2 l=   2 prim: PRINTABLESTRING   :US 178:d=3 hl=2 l=  19 cons: SET 180:d=4 hl=2 l=  17 cons: SEQUENCE 182:d=5 hl=2 l=   3 prim: OBJECT            :organizationName 187:d=5 hl=2 l=  10 prim: PRINTABLESTRING   :Apple Inc.  199:d=3  hl=2 l=  38 cons: SET 201:d=4 hl=2 l=  36 cons: SEQUENCE 203:d=5 hl=2 l=   3 prim: OBJECT            :organizationalUnitName 208:d=5 hl=2 l=  29 prim: PRINTABLESTRING   :Apple Certification Authority 239:d=3 hl=2 l=  22 cons: SET 241:d=4 hl=2 l=  20 cons: SEQUENCE 243:d=5 hl=2 l=   3 prim: OBJECT            :commonName 248:d=5 hl=2 l=  13 prim: PRINTABLESTRING   :Apple Root CA  263:d=2  hl=4 l= 290 cons: SEQUENCE 267:d=3 hl=2 l=  13 cons: SEQUENCE 269:d=4 hl=2 l=   9 prim: OBJECT            :rsaEncryption 280:d=4 hl=2 l=   0 prim: NULL 282:d=3 hl=4 l= 271 prim: BIT STRING 557:d=2 hl=4 l= 378 cons: cont [ 3 ] 561:d=3 hl=4 l= 374 cons: SEQUENCE 565:d=4 hl=2 l=  14 cons: SEQUENCE 567:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Key Usage 572:d=5 hl=2 l=   1 prim: BOOLEAN           :255 575:d=5 hl=2 l=   4 prim: OCTET STRING      [HEX DUMP]:03020106 581:d=4 hl=2 l=  15 cons: SEQUENCE 583:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Basic Constraints 588:d=5 hl=2 l=   1 prim: BOOLEAN           :255 591:d=5 hl=2 l=   5 prim: OCTET STRING      [HEX DUMP]:30030101FF 598:d=4 hl=2 l=  29 cons: SEQUENCE 600:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Subject Key Identifier 605:d=5 hl=2 l=  22 prim: OCTET STRING      [HEX DUMP]:04142BD06947947609FEF46B8D2E40A6F7474D7F085E 629:d=4 hl=2 l=  31 cons: SEQUENCE 631:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Authority Key Identifier 636:d=5 hl=2 l=  24 prim: OCTET STRING      [HEX DUMP]:301680142BD06947947609FEF46B8D2E40A6F7474D7F085E 662:d=4 hl=4 l= 273 cons: SEQUENCE 666:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Certificate Policies 671:d=5 hl=4 l= 264 prim: OCTET STRING      [HEX DUMP]:308201043082010006092A864886F7636405013081F2302A06082B0601050507 0201161E68747470733A2F2F7777772E6170706C652E636F6D2F6170706C6563 612F3081C306082B060105050702023081B61A81B352656C69616E6365206F6E 207468697320636572746966696361746520627920616E792070617274792061 7373756D657320616363657074616E6365206F6620746865207468656E206170 706C696361626C65207374616E64617264207465726D7320616E6420636F6E64 6974696F6E73206F66207573652C20636572746966696361746520706F6C6963 7920616E642063657274696669636174696F6E20707261637469636520737461 74656D656E74732E 939:d=1 hl=2 l=  13 cons: SEQUENCE 941:d=2 hl=2 l=   9 prim: OBJECT            :sha1WithRSAEncryption 952:d=2 hl=2 l=   0 prim: NULL 954:d=1 hl=4 l= 257 prim: BIT STRING 1215:d=0 hl=4 l=1016 cons: SEQUENCE 1219:d=1 hl=4 l= 736 cons: SEQUENCE 1223:d=2 hl=2 l=   3 cons: cont [ 0 ] 1225:d=3 hl=2 l=   1 prim: INTEGER           :02 1228:d=2 hl=2 l=   1 prim: INTEGER           :10 1231:d=2 hl=2 l=  13 cons: SEQUENCE 1233:d=3 hl=2 l=   9 prim: OBJECT            :sha1WithRSAEncryption 1244:d=3 hl=2 l=   0 prim: NULL 1246:d=2 hl=2 l=  98 cons: SEQUENCE 1248:d=3 hl=2 l=  11 cons: SET 1250:d=4 hl=2 l=   9 cons: SEQUENCE 1252:d=5 hl=2 l=   3 prim: OBJECT            :countryName 1257:d=5 hl=2 l=   2 prim: PRINTABLESTRING   :US 1261:d=3 hl=2 l=  19 cons: SET 1263:d=4 hl=2 l=  17 cons: SEQUENCE 1265:d=5 hl=2 l=   3 prim: OBJECT            :organizationName 1270:d=5 hl=2 l=  10 prim: PRINTABLESTRING   :Apple Inc. 1282:d=3  hl=2 l=  38 cons: SET 1284:d=4 hl=2 l=  36 cons: SEQUENCE 1286:d=5 hl=2 l=   3 prim: OBJECT            :organizationalUnitName 1291:d=5 hl=2 l=  29 prim: PRINTABLESTRING   :Apple Certification Authority 1322:d=3 hl=2 l=  22 cons: SET 1324:d=4 hl=2 l=  20 cons: SEQUENCE 1326:d=5 hl=2 l=   3 prim: OBJECT            :commonName 1331:d=5 hl=2 l=  13 prim: PRINTABLESTRING   :Apple Root CA 1346:d=2  hl=2 l=  30 cons: SEQUENCE 1348:d=3 hl=2 l=  13 prim: UTCTIME           :070105192159Z 1363:d=3 hl=2 l=  13 prim: UTCTIME           :220105192159Z 1378:d=2 hl=2 l= 126 cons: SEQUENCE 1380:d=3 hl=2 l=  11 cons: SET 1382:d=4 hl=2 l=   9 cons: SEQUENCE 1384:d=5 hl=2 l=   3 prim: OBJECT            :countryName 1389:d=5 hl=2 l=   2 prim: PRINTABLESTRING   :US 1393:d=3 hl=2 l=  19 cons: SET 1395:d=4 hl=2 l=  17 cons: SEQUENCE 1397:d=5 hl=2 l=   3 prim: OBJECT            :organizationName 1402:d=5 hl=2 l=  10 prim: PRINTABLESTRING   :Apple Inc. 1414:d=3  hl=2 l=  38 cons: SET 1416:d=4 hl=2 l=  36 cons: SEQUENCE 1418:d=5 hl=2 l=   3 prim: OBJECT            :organizationalUnitName 1423:d=5 hl=2 l=  29 prim: PRINTABLESTRING   :Apple Certification Authority 1454:d=3 hl=2 l=  50 cons: SET 1456:d=4 hl=2 l=  48 cons: SEQUENCE 1458:d=5 hl=2 l=   3 prim: OBJECT            :commonName 1463:d=5 hl=2 l=  41 prim: PRINTABLESTRING   :Apple Secure Boot Certification Authority 1506:d=2 hl=4 l= 290 cons: SEQUENCE 1510:d=3 hl=2 l=  13 cons: SEQUENCE 1512:d=4 hl=2 l=   9 prim: OBJECT            :rsaEncryption 1523:d=4 hl=2 l=   0 prim: NULL 1525:d=3 hl=4 l= 271 prim: BIT STRING 1800:d=2 hl=3 l= 156 cons: cont [ 3 ] 1803:d=3 hl=3 l= 153 cons: SEQUENCE 1806:d=4 hl=2 l=  14 cons: SEQUENCE 1808:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Key Usage 1813:d=5 hl=2 l=   1 prim: BOOLEAN           :255 1816:d=5 hl=2 l=   4 prim: OCTET STRING      [HEX DUMP]:03020186 1822:d=4 hl=2 l=  15 cons: SEQUENCE 1824:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Basic Constraints 1829:d=5 hl=2 l=   1 prim: BOOLEAN           :255 1832:d=5 hl=2 l=   5 prim: OCTET STRING      [HEX DUMP]:30030101FF 1839:d=4 hl=2 l=  29 cons: SEQUENCE 1841:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Subject Key Identifier 1846:d=5 hl=2 l=  22 prim: OCTET STRING      [HEX DUMP]:0414493D3653C9D715E186614EACABAB1856635DC3C6 1870:d=4 hl=2 l=  31 cons: SEQUENCE 1872:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Authority Key Identifier 1877:d=5 hl=2 l=  24 prim: OCTET STRING      [HEX DUMP]:301680142BD06947947609FEF46B8D2E40A6F7474D7F085E 1903:d=4 hl=2 l=  54 cons: SEQUENCE 1905:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 CRL Distribution Points 1910:d=5 hl=2 l=  47 prim: OCTET STRING      [HEX DUMP]:302D302BA029A0278625687474703A2F2F7777772E6170706C652E636F6D2F61 70706C6563612F726F6F742E63726C 1959:d=1 hl=2 l=  13 cons: SEQUENCE 1961:d=2 hl=2 l=   9 prim: OBJECT            :sha1WithRSAEncryption 1972:d=2 hl=2 l=   0 prim: NULL 1974:d=1 hl=4 l= 257 prim: BIT STRING 2235:d=0 hl=4 l= 927 cons: SEQUENCE 2239:d=1 hl=4 l= 563 cons: SEQUENCE 2243:d=2 hl=2 l=   3 cons: cont [ 0 ] 2245:d=3 hl=2 l=   1 prim: INTEGER           :02 2248:d=2 hl=2 l=   9 prim: INTEGER           :FB01FB0000000001 2259:d=2 hl=2 l=  13 cons: SEQUENCE 2261:d=3 hl=2 l=   9 prim: OBJECT            :sha1WithRSAEncryption 2272:d=3 hl=2 l=   0 prim: NULL 2274:d=2 hl=2 l= 126 cons: SEQUENCE 2276:d=3 hl=2 l=  11 cons: SET 2278:d=4 hl=2 l=   9 cons: SEQUENCE 2280:d=5 hl=2 l=   3 prim: OBJECT            :countryName 2285:d=5 hl=2 l=   2 prim: PRINTABLESTRING   :US 2289:d=3 hl=2 l=  19 cons: SET 2291:d=4 hl=2 l=  17 cons: SEQUENCE 2293:d=5 hl=2 l=   3 prim: OBJECT            :organizationName 2298:d=5 hl=2 l=  10 prim: PRINTABLESTRING   :Apple Inc. 2310:d=3  hl=2 l=  38 cons: SET 2312:d=4 hl=2 l=  36 cons: SEQUENCE 2314:d=5 hl=2 l=   3 prim: OBJECT            :organizationalUnitName 2319:d=5 hl=2 l=  29 prim: PRINTABLESTRING   :Apple Certification Authority 2350:d=3 hl=2 l=  50 cons: SET 2352:d=4 hl=2 l=  48 cons: SEQUENCE 2354:d=5 hl=2 l=   3 prim: OBJECT            :commonName 2359:d=5 hl=2 l=  41 prim: PRINTABLESTRING   :Apple Secure Boot Certification Authority 2402:d=2 hl=2 l=  30 cons: SEQUENCE 2404:d=3 hl=2 l=  13 prim: UTCTIME           :070106052052Z 2419:d=3 hl=2 l=  13 prim: UTCTIME           :170106052052Z 2434:d=2 hl=2 l= 116 cons: SEQUENCE 2436:d=3 hl=2 l=  11 cons: SET 2438:d=4 hl=2 l=   9 cons: SEQUENCE 2440:d=5 hl=2 l=   3 prim: OBJECT            :countryName 2445:d=5 hl=2 l=   2 prim: PRINTABLESTRING   :US 2449:d=3 hl=2 l=  19 cons: SET 2451:d=4 hl=2 l=  17 cons: SEQUENCE 2453:d=5 hl=2 l=   3 prim: OBJECT            :organizationName 2458:d=5 hl=2 l=  10 prim: PRINTABLESTRING   :Apple Inc. 2470:d=3  hl=2 l=  50 cons: SET 2472:d=4 hl=2 l=  48 cons: SEQUENCE 2474:d=5 hl=2 l=   3 prim: OBJECT            :organizationalUnitName 2479:d=5 hl=2 l=  41 prim: PRINTABLESTRING   :Apple Secure Boot Certification Authority 2522:d=3 hl=2 l=  28 cons: SET 2524:d=4 hl=2 l=  26 cons: SEQUENCE 2526:d=5 hl=2 l=   3 prim: OBJECT            :commonName 2531:d=5 hl=2 l=  19 prim: PRINTABLESTRING   :S5L8900 Secure Boot 2552:d=2 hl=3 l= 159 cons: SEQUENCE 2555:d=3 hl=2 l=  13 cons: SEQUENCE 2557:d=4 hl=2 l=   9 prim: OBJECT            :rsaEncryption 2568:d=4 hl=2 l=   0 prim: NULL 2570:d=3 hl=3 l= 141 prim: BIT STRING 2714:d=2 hl=2 l=  90 cons: cont [ 3 ] 2716:d=3 hl=2 l=  88 cons: SEQUENCE 2718:d=4 hl=2 l=  11 cons: SEQUENCE 2720:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Key Usage 2725:d=5 hl=2 l=   4 prim: OCTET STRING      [HEX DUMP]:03020780 2731:d=4 hl=2 l=   9 cons: SEQUENCE 2733:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Basic Constraints 2738:d=5 hl=2 l=   2 prim: OCTET STRING      [HEX DUMP]:3000 2742:d=4 hl=2 l=  29 cons: SEQUENCE 2744:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Subject Key Identifier 2749:d=5 hl=2 l=  22 prim: OCTET STRING      [HEX DUMP]:041419DFD743A6C35716ED8642DDB29408A16AEDDFDE 2773:d=4 hl=2 l=  31 cons: SEQUENCE 2775:d=5 hl=2 l=   3 prim: OBJECT            :X509v3 Authority Key Identifier 2780:d=5 hl=2 l=  24 prim: OCTET STRING      [HEX DUMP]:30168014493D3653C9D715E186614EACABAB1856635DC3C6 2806:d=1 hl=2 l=  13 cons: SEQUENCE 2808:d=2 hl=2 l=   9 prim: OBJECT            :sha1WithRSAEncryption 2819:d=2 hl=2 l=   0 prim: NULL 2821:d=1 hl=4 l= 341 prim: BIT STRING
 * openssl asn1parse -inform DER -in cert

GUI
Instead of parsing the data, you can also just save the IMG3 CERT part to a file with .cer file extension on a Windows system and can graphically look through the certificate details.